ANALOGS OF PTH

Abstract: PTH compounds having PTH-like activity and comprising at least one modification, said modification being either 1) at least one radical selected from an L- or D-(alpha)-amino acid, C2-6alcoxycarbonyl and optionally substituted C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aralkyl, aralkenyl or C3-6cycloalkyl-C1-4alkyl and attached to the terminal amino group of the PTH compound, and/or at least one radical selected from C2-6alcoxycarbonyl and optionally substituted C1-8alkyl, C2-8alkenyl, C2-8alkynyl, aralkyl, aralkenyl or C3-6cycloalkyl-C1-4alkyl and attached to one or more side chain amino groups of the PTH compound; or 2) at least one (alpha)-amino acid unit in the positions 1 to 38 of a naturally occurring PTH sequence being replaced by a natural or unnatural amino acid unit optionally in protected form, whereby the (alpha)-amino acid units present in positions 1 and 2 at the amino terminus of the PTH sequence may be replaced by a pseudo-peptide, or a combination of such modifications, in free form or in salt form, have pharmacological activity, e.g. for preventing or treating all bone conditions which are associated with increased calcium depletion or resorption or in which calcium fixation in the bone is desirable.

Description: ANALOGS OF PTH The present invention relates to variants of parathyroid hormone (PTH.) , a process for their production, pharmaceutical preparations conprising them and their use as a pharmaceutical. The term "PTH" as used herein refers to any genetically encoded form of parathyroid hormone, including the mature form containing 84 amino acids of a given vertebrate PTH species, e.g human, porcine, rat, bovine, chicken, and fragments thereof as well as analogues and derivatives thereof having PTH-like activity. The position of each amino acid involved in the PTH sequence is numbered according to the internationally accepted procedure. For consistency and as is conventional, in the following description, the same numbering system will be applied to the amino acids of the PTH sequence independently of the substitution pattern in the molecule. More particularly, the present invention provides a PTH conpound having PTH-like activity and conprising at least one modification, said modi¬ fication being either 1. at least one radical selected from a L- or D-α-amino acid, • C 2 - 6 alcoxycarbonyl and optionally substituted Ci-galkyl, C 2 -salkenyl, C 2 - 8 aikynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ alkyl and attached to the terminal amino group of the PTH compound, and/or at least one radical selected from C 2 - 6 alcoxycarbonyl and optionally substituted Ci-galkyl, C 2 - 8 alkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ alkyl and attached to one or more side chain amino groups of the PTH compound, or 2. at least one α-amino acid unit in the positions 1 to 38 of a naturally occurring PTH sequence being replaced by a natural or unnatural amino acid unit optionally in protected form, whereby the α-amino acid units present in positions 1 and 2 at the amino terminus of the PTH sequence together may be replaced by a pseudo-peptide, or a combination of such modifications, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 alcoxycarbonyl or optionally substituted Cι_ 8 alkyl, C 2 - 8 alkenyl, C 2 - 8 alkynyl, aralkyl, C 2 - 8 alkynyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 1 is Gly, D-Ser, D-Ala or Tyr; or ii. the α-amino acid in position 2 is Ala, D-Val, Lys, Arg or Cit and the α-amino acid in position 34 is Tyr; or the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr and optionally the α-amino acids in positions 8 and 18 are each Nle; or iii. the α-amino acid in positions 3 and/or 6 and/or 9 are replaced by a natural or unnatural amino acid; or iv. the α-amino acid in position 23 is replaced by Ala, Arg, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Lys, Met, Pro, Ser or Thr; or v. the α-amino acid in position 25 and/or 26 and/or 27 is replaced by Ala, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr or Val; or vi. the α-amino acids in positions 8 and 18 are each Nle or each Met(O) and optionally the α-amino acid in position 34 is Tyr; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 34 is Tyr and either the α-amino acid in position 12 is L- or D-Pro, L- or D-Ala, Aib or NMeGly or the α-amino acid in position 23 is Phe, Leu, Nle, Val, Tyr, α-Nal or β-Nal; or vii. the α-amino acid in position 28 is Lys and the α-amino acid in position 30 is Leu; or viii. the α-amino acid in position 1 is Aib; and/or the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp; and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr; and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl) , D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys(Fmoc), D-Phe or D-Asn; and/or the α-amino acid in position 13 is Leu; and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His; and/or the α-amino acid in position 23 is 2-(l,3-dithiolane- 2-yl)Trp; and/or the α-amino acid in position 25 and/or in position 26 is His; and/or the α-amino acid in position 27 is Gin or Leu; or ix. the α-amino acid in position 8 and/or 18 is Ala or Ser; or the α-amino acid in position 8 and/or 18 is Ala, Val, Leu, He, Ser or Trp and the α-amino acid in position 34 is Tyr; or the PTH compound is other than PTH(1-84) wherein i. the α-amino acid in position 1 is Tyr, Val, Pro, Asp or Cys; or ii. the α-amino acid in position 2 is Ala, Glu, Leu, Ser or Arg; or iii. the α-amino acid in positions 3 and/or 6 and/or 9 are replaced by a natural or unnatural amino acid; or iv. the α-amino acid in position 23 is replaced by Ala, Arg, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Lys, Met, Pro, Ser or Thr; or v. . the α-amino acid in position 25 and/or 26 and/or 27 is replaced by Ala, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr or Val; or vi. the α-amino acid in position 8 is Met, Met(O), Ala, Val, Leu, He, Ser, Trp, Asn, Gin, Asp, Glu, Lys, Arg, Tyr or Gly and the α-amino acid in position 18 is Leu; or the α-amino acid in position 8 and/or 18 is Ala, Val, Leu, He, Ser or Trp, and optionally the α-amino acid in position 34 is Tyr; or the α-amino acid in position 8 and in position 18 are each Met(O); or the α-amino acid in position 8 is Leu and the α-amino acid in position 18 is Met(O); or vii. the α-amino acid in position 26 is Gin; the compound is other than Pro°PTH(l-84) or [Met 0 ,Leu 8 ,Leu 18 ]PTH(1-84) ; or the PTH compound is other than hPTH(l-36) wherein the α-amino acid in position 36 is Leu; in free form or in salt form or complex form. When the PTH sequence is derived from a PTH fragment, it is a PTH fragment having PTH-like activity and comprising at least the first 27 N-terminal amino acid units of PTH, preferably up to the first 38 N-terminal amino acid units of PTH, e.g. 1-34 to 1-38, e.g. 1-34, 1-36, 1-37 or 1-38 PTH, at least one of the α-amino acids being replaced according to the invention. One or more α-amino acid units normally present in the naturally occurring PTH sequence may also be omitted. hPTH fragments, particularly hPTH(l-34) and hPTH(l-36), are preferred. The C-terminus of the PTH compounds may be -C00H, esterified -C00H, e.g. -COG.. a wherein R a is lower alkyl, for example Cι_ 4 alkyl, -CONH2 or a mono- or disubstituted amide, e.g. -C0NR b R c wherein one of R b and R c is H and the other is an aliphatic residue, e.g. C ! _ 6 alkyl, or both are an aliphatic residue, or R b and R c together with the nitrogen atom to which they are attached form a heterocyclic residue, e.g. pyrrolidinyl or piperidinyl. Hereinafter, these compounds will be referred to as compounds of the invention. "Natural amino acids" refer to those well known in the art. They are listed and standard abbreviations are provided in the U.S.P.T.O. publication, Trademark Official Gazette, published May 15, 1990, p. 33 at 46. These amino acids and abbreviations are specifically incorporated herein by reference. The natural amino acids are shown below: The term "unnatural amino acid" unit means an amino acid unit which is not genetically encoded. Examples of unnatural amino acid units include e.g. the D isomers of the natural α-amino acids as indicated above, Aib (amino-isobutyric acid), bAib (3-aminoisobutyric acid), Nva (norvaline) , β-Ala, Aad (2-amino- adipic acid), bAad (3-aminoadipic acid), Abu (2-aminobutyric acid), Gaba (γ-aminobutyric acid), Acp (6-aminocaρroic acid), Dbu (2,4-diaminobutyric acid), TMSA (trimethylsilyl-Ala) , alle (allo-Isoleucine) , Nle (Norleucine) , tert.Leu, Cit (Citrulline) , Orn, Dpm (2,2'-diaminopimelic acid), Dpr (2,3-diaminopropionic acid), α-or β-Nal, Cha(cyclohexyl-Ala) , hydroxy-proline, Sar (Sarcosine) etc., cyclic amino acid units and N -alkylated amino acid units, e.g. MeGly (N α -Methyl-glycine) , EtGly (N -ethylglycine) , EtAsn (N α -ethyl-asparagine) . By amino acid in protected form is meant a natural or unnatural amino acid having e.g. a side chain including an heteroatom such as 0, S or N which can be protected with an 0-, S- or N-protecting group. The N-terminus of the PTH compounds of the invention may also be in protected form. N-protecting groups as may be present on the N-terminus or side chain amino groups of amino acid units include such groups as e.g. disclosed in "Protective Groups in Organic Synthesis", T. W. Greene, J.Wiley & Sons NY (1981), 219-287, for example acyl such as formyl, acetyl, trifluoroacetyl, methoxysuccinyl, hydroxysuccinyl or benzoyl optionally substituted on the phenyl ring with e.g. p-methoxycarbonyl, p-methoxy, p-nitro or p-phenylsulfonamidocarbonyl; alkoxycarbonyl such as t-butyloxycarbonyl, isobutyloxycarbonyl or methoxycarbonyl; allylcxycarbonyl; trityl; 2,2,5,7,8-pentamethyl-chroman-6- sulfonyl; arylmethoxycarbonyl such as 9-fluorenylmethoxycarbonyl or benzyloxy carbonyl optionally substituted on the phenyl ring with p-methoxy, p-nitro, o- or p-chloro, m-phenyl or 3,4-dimethyl; arylmethyl such as benzyl optionally ring substituted with p-methoxy, p-nitro or p-chloro; or arylsulfonyl such as phenylsulfonyl optionally ring substituted with p-methyl or p-methoxy, or naphthylsulfonyl optionally ring substituted with e.g. amino or di (Cι_ 4 alkyl)amino. O-protecting groups of 0-containing side chains are e.g. as described in "The Peptides", 3, (1981), E. Gross and J. Meien- hofer (Ed.) . For aliphatic hydroxy functionalities, suitable O-protecting groups are e.g. as disclosed in the above reference in "Protection of the Hydroxy Group", J.M. Stewart, 169-201 and include the benzyl, t.-butyl and methyl groups. For aromatic hydroxy functionalities, suitable O-protecting groups include the benzyl, t.-butyl, methyl, tosyl and benzyloxycarbonyl groups. O-protecting groups for carboxy functionalities on amino acid side chains are well known ester groups and described e.g. in "The Peptides", 3, 101-135 ("Carboxyl Protecting Groups" by R.W. Roeske) and include the methyl, ethyl, t.-butyl and benzyl groups. S-protecting groups for thiol functionalities on amino acid side chains are known and described e.g. in "The Peptides", 3, 137-167 ("Sulfhydryl Group Protection" by R.G. Hiskey) . Examples include the methyl, t.-butyl, benzyl, p-methoxyphenyl- methyl, ethylamino-carbonyl and benzyloxycarbonyl groups. According to the invention the PTH compounds may bear on their terminal amino group at least one radical selected from a L- or D-α-amino acid, C 2 - 6 alkoxycarbonyl and optionally substituted Ci-s lkyl, C 2 - 8 alkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ alkyl, and/or on one or more side chain amino group(s) at least one radical selected from C 2 - 6 lkoxycarbonyl and optionally substituted Cι_galkyl, C 2 - 8 lkenyl, C 2 -βal ynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-C 1 _ alkyl. When such a group is attached to a side chain amino group, it is preferably on the ε -amino group of a Lys unit. Preferred substituents for the alkyl, alkenyl, aralkyl, aralkenyl or cycloalkylalkyl group are hydroxy, amino and for the aryl moiety also halogen and/or Cχ_ 4 alkoxy. The alkyl group or alkyl moiety may be linear or branched and optionally interrupted by 0, S or N. Preferably any Ci-salkyl, C2-salkenyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl on the amino group of a PTH compound, is non-substituted. Examples for Cι_ 8 alkyl are Cχ_ealkyl, preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t.-butyl; for C 2 -salkenyl, C 2 - 4 alkenyl, preferably allyl; for C 2 - 8 alkynyl, C 2 - alkynyl, preferably prop-2-ynyl; for aralkyl, phenyl or benzyl; for aralkenyl, styryl; for C 3 _ 6 cyclo- alkyl-Cι_ 4 alkyl, cyclohexyl-methyl. C 2 - 6 lkoxycarbonyl is preferably forr. 1 or acetyl. Suitable examples of D- or L-α-amino acids attached to the N-terminus include e.g. D- or L- Pro, Ala. Preferred substituents when present are alkyl, alkynyl, alcoxy- carbonyl or a D- or L-α-amino acid attached to the N-terminus of the PTH compound and/or at least one alkyl or alkoxycarbonyl attached to one or more side chain amino groups. Preferred PTH compounds of the invention are those comprising at least one amino acid unit replaced in one of the following positions of the PTH sequence: 1, 2, 3, 8-11, 13 to 19, 21, 22, 29 to 34, particularly 8-11, 16-19, 33 and/or 34. Further preferred PTH compounds of the invention are those comprising more than one amino acid unit replaced, particularly more than two amino acid units, more particularly more than three amino acid units, especially from 5 to 7 amino acid units replaced, preferably at any combination of the above mentioned positions of the PTH sequence. In a series of specific or alternative embodiments, the present invention provides a PTH compound as disclosed above wherein in particular the α-amino acids in positions 1 and 2 at the amino terminus of the PTH sequence are replaced by a pseudo-dipeptide. The term "pseudo-dipeptide" as used herein refers to a dipeptide isostere in which the peptide bond between the 2 amino acid residues, whether natural or unnatural, is replaced with any isosteric group, e.g. -CH 2 -NH-, -C(Halogen)=CH- or -C(alkyl)=CH-. Examples of compounds of the invention wherein the α-amino acids in positions 1 and 2 are replaced by a pseudo-dipeptide include e.g compounds of formula I X - Pi I wherein X is a residue of formula (a) Y I Z-N - CH - C = CH - CH - CO- (a) I I I v w Y' or (b) Y a Z" I I Z-N - C - CH 2 - N - CH - CO- (b) I I I Z' Y b Y' wherein each of Z and Z', independently, is H; optionally substituted Cι_salkyl, C 2 -βalkenyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl; or a protecting group, at most one of Z and V being a protecting group, Z" is H, Cι_ 8 alkyl or a protecting group each of Y and Y' , independently, is an optionally protec¬ ted side chain of a natural or unnatural α-amino acid, one of Y a and Y b is hydrogen and the other is an optionally protected side chain of a natural or unnatural α-amino acid or Y a and Y b form together with the carbon atom to which they are attached a C 3 _ 6 cycloal yl group, and W is halogen or Cι_ 4 alkyl, or W and Y' together with the moiety —C=CH-CH- I I to which they are attached, form an optionally substituted aromatic cyclic or heterocyclic residue, and Pi is a PTH sequence, as defined above, in which amino acid units in positions 1 and 2 of the N-terminus are omitted, in free form or in salt or complex form. In compounds of formula I, P x may be a fragment (3-z) of PTH wherein z is 84 or an integer from 27 to 38, preferably from 34 to 38, particularly 34, 36, 37 or 38, especially 34 or 36. The PTH sequence represented by Pi may correspond either to a naturally occurring PTH sequence, or to a naturally occurring PTH sequence wherein at least one α-amino acid unit has been replaced by a natural or unnatural amino acid optionally in protected form and/or one or more α-amino acid units are also omitted. P x may also comprise at least one side chain amino group substituted as disclosed above. Halogen is preferably fluorine or chlorine. In the residue of formula (a) , the double bond has preferably the configuration trans (E) . As residue attaching to the α-carbon atom of a natural α-amino acid, Y, Y' , Y a or Y b may be the side chain present in a natural α-amino acid as listed above, e.g. as present in Gly (i.e. H) , Ala, Val, Ser, Leu, He, Phe, Trp. Y, Y' , Y a or Y may also be the residue attaching to the α-carbon atom of an unnatural α-amino acid as indicated above, e.g. as present in Nva, Orn, Abu, Aib, Nle. If the side chain of the natural or unnatural amino acids as Y, Y' , Y a or Y includes heteroatoms such as 0, S or N, the heteroatoms on the side chain may optionally be pro- tected with an 0-, S- or N-protecting group, e.g. as indicated above. Protecting groups as Z or Z' or Z" may be as disclosed above. Ci-salkyl as Z or V or Z" may be as indicated above. Preferably Z or V is hydrogen or Cι_ 4 alkyl, particularly hydrogen or methyl. Preferably Y is H or CH 3 . When W is Cχ_ alkyl, it is preferably CH 3 . When W and Y' together with the moiety to which they are attached form an optionally substituted aromatic cyclic or heterocyclic residue, it may be an aromatic 5- or 6-membered cyclic residue comprising optionally 1 or 2 heteroatoms selected from N, S and 0, e.g. phenyl, imidazolyl, pyridyl, oxazolyl or thiazolyl. A preferred substituent is hydroxy or methoxy, particularly for the phenyl ring. Y' is preferably H, CH 3 , isopropyl or benzyl. When Z" is Cι_ 8 alkyl, it is preferably CH 3 , C 2 H 5 or isopropyl. C 3 _ 6 cycloalkyl as Y a and Y b together is preferably cyclopropyl or cyclopentyl. When Z" is a protecting group, it is preferably acyl, particularly acetyl. In a series of specific and alternative embodiments, the present invention provides a PTH compound as disclosed above wherein the α-amino acid unit in position 1 and/or the α-amino acid unit in position 2 of the N-terminus of the PTH sequence is replaced by an optionally protected natural or unnatural amino acid residue, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 lkoxycarbonyl or optionally substituted Cι_ 8 alkyl, C 2 - 8 alkenyl, C 2 -βalkynyl, aralkyl, aralkenyl or C 3 _ 6 Cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 1 is Aib, Gly, D-Ser, D-Ala or Tyr; or ii. the α-amino acid in position 2 is Ala, D-Val, Lys, Cit or Arg and the α-amino acid in position 34 is Tyr; or the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr and optionally the α-amino acids in positions 8 and 18 are each Nle; or iii. the α-amino acid in position 1 is Aib and at least one further α-amino acid unit has been replaced as follows: the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp, and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr, and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl), D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys(Fmoc), D-Phe or D-Asn, and/or the α-amino acid in position 13 is Leu, and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His, and/or the α-amino acid in position 23 is 2-(l,3-dithiolane-2-yl)Trp, and/or the α-amino acid in position 25 and/or in position 26 is His, and/or the α-amino acid in position 27 is Gin or Leu, or the PTH compound is other than PTH(1-84) wherein i. the α-amino acid in position 1 is Tyr, Val, Pro, Asp or Cys; or ii. the α-amino acid in position 2 is Ala, Glu, Leu, Ser or Arg. Examples of compounds of the invention wherein the α-amino acids in position 1 and/or in position 2 are replaced as indicated above include e.g compounds of formula II Xla - ?2a - P 2 H wherein Xι a is a residue of an optionally protected natural α-amino acid or a residue of formula (Ha) Ri I Z a -N -[C] n - CO - (Ha) I I Z'a R2 wherein each of Z a and Z' a , independently, is H, Cι_ 6 alkyl or a protecting group, at most one of Z a and Z' a being a protecting group, and either n is 1 and i. each of R x and R , independently, is Cι_ 6 alkyl, or ii. one of Ri and R is methyl or ethyl and the other is an optionally protected residue attaching to the α-carbon atom of a natural α-amino acid other than Ala, Leu, He or Val, or iii.one of Ri and R is H, methyl or ethyl and the other is an optionally protected residue attaching to the α-carbon atom of an unnatural α-amino acid, or iv. Ri and R 2 form together with the carbon atom to which they are attached a C 3 _ 6 cycloalkyl group, or Ri I v. the residue Z a - N - C - represents a heterocyclic I I Z'a R2 residue optionally condensed to a benzene ring, or n is 2, 3, 4 or 5 and each of Ri and R 2 is H or CH 3 , Y 2a is a residue of an optionally protected natural α-amino acid or a residue of formula (lib) R3 I -N -[C] m - CO - (lib) I I Z b R 4 Z b is H or Cι_ 6 alkyl and either m is 1 and i. each of R 3 and R , independently, is Cι_ 6 alkyl, or ii. one of R 3 and R 4 is methyl or ethyl and the other is an optionally protected residue attaching to the α-carbon atom of a natural α-amino acid other than Ala, Leu, He or Val, or iii.one of R 3 and R is H, methyl or ethyl and the other is an optionally protected residue attaching to the α-carbon atom of an unnatural α-amino acid, or m is 2, 3, 4 or 5 and each of R 3 and R is H or CH 3 , and P 2 is a PTH sequence as defined above in which amino acid units in positions 1 and/or 2 of the N-terminus are omitted. Ri When the residue Z a - N - C - is a heterocyclic residue I I Z'a 2 optionally condensed to a benzene ring, it may be a residue derived from a saturated or unsaturated 5- or 6-membered heterocycle comprising one or more heteroatoms selected from N, 0 and S. Examples of such heterocyclic residues include e.g. 2-pyridyl, 3-morpholinyl, hexahydropyridazinyl, 2- or 3-indolyl. When n or m is > 1, the moiety CR 1 R 2 or CR 3 R may be -CH(CH 3 )-CH 2 -, propyl, butyl or pentyl. C 3 _ 6 cycloalkyl as Ri and R 2 together is preferably cyclopropyl or cyclopentyl. As residue attaching to the α-carbon atom of a natural α-amino acid, Ri, R 2 , R 3 or R 4 may be the side chain present in a natural α-amino acid as listed above, e.g. as present in Gly, Ser or Thr. One of Ri and R or one of R 3 and R 4 may be methyl or ethyl and the other may be CH 3 , isopropyl, isobutyl or CH 3 -CH 2 -CH(CH 3 ) -. Ri, 2 r R 3 ° r R 4 ma Y also be the residue attaching to the α-carbon atom of an unnatural α-amino acid as indicated above, e.g. as present in Abu, Gaba, Nva, Aib, TMSA or Nle. If the side chain of the natural or unnatural amino acids as Ri, R 2 , R 3 or R includes heteroatoms such as 0, S or N, the heteroatoms on the side chain may optionally be protected with an 0-, S- or N-protecting group, e.g. as indicated above. Protecting group as Z a or Z' a may be as disclosed above. Cι_ 6 alkyl as Z b is preferably methyl or ethyl. Preferably Z b is H. Cι_ 6 alkyl as Z a or Z' a is preferably straight chain or branched Cι_ 4 alkyl. Preferably one of Z a and Z' a is H and the other is H, Cι_ 4 alkyl or a protecting group, particularly H. In a further or alternative embodiment, the present invention also provides a PTH compound as disclosed above wherein the α-amino acid unit in position 8 and/or the α-amino acid unit in position 18 is replaced by an optionally protected natural or unnatural amino acid residue, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 alkoxycarbonyl or optionally substituted Ci-salkyl, C 2 -s lkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acids in positions 8 and 18 are each Nle or each Met(O) and optionally the α-amino acid in position 34 is Tyr; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 34 is Tyr and either the α-amino acid in position 12 is L- or D-Pro, L- or D-Ala, Aib or NMeGly or the α-amino acid in position 23 is Phe, Leu, Nle, Val, Tyr, α-Nal or β-Nal; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr; or ii. the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp and optionally at least one further α-amino acid unit has been replaced as follows: the α-amino acid in position 1 is Aib and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr, and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl), D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys(Fmoc), D-Phe or D-Asn, and/or the α-amino acid in position 13 is Leu, and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His, and/or the α-amino acid in position 23 is 2- (l,3-dithiolane-2-yl)Trp, and/or the α-amino acid in position 25 and/or in position 26 is His, and/or the α-amino acid in position 27 is Gin or Leu; or iii. the α-amino acid in position 8 and/or 18 is Ala or Ser; or the α-amino acid in position 8 and/or 18 is Leu, and the α-amino acid in position 34 is Tyr; or the PTH compound is other than PTH(1-84) wherein the α-amino acid in position 8 is Met, Met(O), Ala, Val, Leu, He, Ser, Trp, Asn, Gin, Asp, Glu, Lys, Arg, Tyr or Gly and the α-amino acid in position 18 is Leu; or the α-amino acid in position 8 and in position 18 are each Met(O); or the α-amino acid in position 8 is Leu and the α-amino acid in position 18 is Met (0) ; or the PTH compound is other than [Leu 18 ,Tyr 34 ]hPTH(l-84) , [Leu 8 ,Tyr 3 ]hPTH(l-84), [Ile 8 ,Leu 18 ,Tyr 34 ]hPTH(l-84) or [Leu 8 ,Leu 18 ,Tyr 34 ]hPTH(l-84) . When the α-amino acid unit in position 8 is replaced by an unnatural amino acid, it may be an unnatural amino acid as disclosed above e.g. Nva, Nle or Cha. Preferably it is an unnatural lipophilic amino acid preferably such containing a straight chain alkyl residue. Nva (norvaline) and its homologues are particularly preferred. The unnatural amino acid in position 8 of the PTH sequence may also be a Cα-methylated or Cα-ethylated natural α-amino acid. Examples of PTH compounds of the invention wherein the α-amino acid unit in position 18 is replaced, are e.g. PTH compounds wherein the α-amino acid residue in position 18 is replaced by a natural amino acid residue such as Gin, Tyr or Lys, for example [Gin 18 ]-PTH, [Lys 18 ]-PTH and [Tyr 18 ]-PTH, particularly [Gin 18 or Lys 18 or Tyr 18 ]-hPTH-(l-x) wherein x is 84 or an integer from 27 to 38, particularly from 34 to 38. Ala in position 18 is also preferred particularly when the PTH sequence is a (1-36) PTH fragment. In these compounds, the amino acid in position 8 may be Met or it may be replaced by an amino acid selected from Leu, He, Val, Phe, Gin, Trp, Ser and Ala or it may be an unnatural lipophilic amino acid residue, e.g. Nva or Nle. Another group of such PTH compounds of the invention comprises e.g. PTH compounds wherein the amino acid residue in position 8 is replaced by an unnatural lipophilic amino acid residue, e.g. Nle or more preferably Nva. In these compounds the amino acid in position 18 may be Met or it may be replaced by an amino acid selected from Leu, He, Val, Phe, Trp, Ser, Ala, Gin, Lys or Tyr, preferably Leu, Gin, Ala or Tyr. A further group of such PTH compounds of the invention are those wherein one or more amino acid units in the remaining positions, e.g. 1 to 7, 9 to 17 and/or 19 to 38 are either omitted or replaced in addition to the replacement of the α-amino acid unit in position 8 and/or 18. In such a case, the α-amino acid in position 8 is preferably replaced by Leu and the α-amino acid in position 18 by Gin, Leu, Ala or Tyr. In a yet further or alternative embodiment, the present invention also provides a PTH compound as disclosed above wherein at least one of the α-amino acid unit of the PTH sequence is replaced by the α-amino acid unit which is present at the corresponding position in PTHrP, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 lkoxycarbonyl or optionally substituted C -galkyl, C 2 -βalkenyl, C 2 -β lk nyl, aralkyl, aralke¬ nyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 8 and/or 18 is Leu; and/or the α-amino acid in position 11 is Lys; and/or the α-amino acid in position 19 and/or 21 is Arg; and/or the α-amino acid in position 25 and/or 26 is His; and/or the α-amino acid in position 27 is Leu; or ii. the α-amino acid in position 25 in Gin and/or the α-amino acid in position 26 is Asn, the α-amino acid in position 27 being optionally Leu; or the PTH compound is other than [Leu 8 ,Leu 18 ]PTH(l-84) . The term "PTHrP" refers to any genetically encoded form of PTHrP, e.g. human, chicken, rat or mouse PTHrP. For consistency and as is conventional, in the following description, the same numbering system will be applied to the amino acids of the PTHrP sequence starting with Ala in position 1 and comprising e.g. Ala in position 38. This group of compounds according to the invention are hybrids between PTH and the homologous PTHrP sequences (referred to herein as PTH-rP hybrids) . The amino acid sequence wherein the substitution according to the invention takes place is from position 1 up to position 38, particularly 1 up to 36, especially 1 up to 34. Preferred PTH compounds of the invention are PTH-rP hybrids wherein more than one α-amino acid unit of the PTH sequence, e.g. at least 2, preferably from 3 to 5 α-amino acid units, are replaced according to the invention. A preferred group of the PTH-rP hybrids according to the invention comprises PTH compounds wherein at least one α-amino acid unit of the PTH α-amino acid sequence in positions 8 to 11, i.e. Met 8 , His 9 , Asn 10 or Leu 11 is replaced by the corresponding α-amino acid unit of the corresponding sequence of PTHrP, i.e. Leu 8 , His 9 , Asp 10 or Lys 11 . The replacement at positions 8 and/or 10 is preferred, particularly at positions 8 and 10. More preferably the α-amino acids at positions 8, 10 and 11 of said PTH sequence are replaced by Leu 8 , Asp 10 and Lys 11 , respectively. Another preferred group of the PTH-rP hybrids according to the invention comprises PTH compounds wherein at least one α-amino acid unit of the PTH α-amino acid sequence in positions 16 to 19 is replaced by the corresponding α-amino acid unit of the corresponding sequence of PTHrP, i.e. Gin 16 , Asp 17 , Leu 18 , Arg 19 . Preferably 3 or all 4 α-amino acids of said sequence are replaced. Particularly preferred are PTH compounds of the invention wherein the α-amino acid in position 16 is Gin, the α-amino acid in position 18 is Leu and the α-amino acid in position 19 is Arg. A further preferred group of the PTH-rP hybrids according to the invention comprises PTH compounds wherein at least one α-amino acid unit of the PTH α-amino acid sequence in positions 33 and 34 is replaced by the corresponding α-amino acid unit of the corresponding sequence of PTHrP, i.e. Thr 33 , Ala 34 . Preferably both α-amino acids are replaced. Yet further preferred groups of the PTH-rP hybrids according to the invention are PTH compounds comprising any combination of the above mentioned α-amino acid substitutions (8-11, 16-19, 33-34), more preferably a combination of substitutions selected from the above indicated 8-11 and 33-34 sequences. As it will be appreciated, in the PTH-rP hybrids according to the invention one or more α-amino acids in positions 1 up to 38 may be further replaced by a natural or unnatural amino acid unit as indicated above or be omitted. In position 10 there may be a α-amino acid selected from Gly, Gin, Glu, His, Ser, Thr or Tyr. In position 13 there may be a D-or L-α-amino acid other than Arg, e.g. Ala, Cys, Gin, He, Asn, Trp, Asp, Val, Ser, Thr, Tyr, Met, Leu or Gly; in position 16 there may be a D- or L-α-amino acid, e.g. Lys, Ser, Leu, Ala, Gin or Gly; in position 17 Ala or Ser or preferably an amino acid having a bigger side chain than Ala or Ser, e.g. Glu, Gin, Phe, His, He or Lys; in position 18 Gin or Tyr; in position 19 Ala, Arg, Val, Tyr, Ser, Lys, Met, His, Gly, Pro, Asn or He; Gin or Arg in position 26; and/or in position 33 a D- or L-α-amino acid e.g. Ser, Thr, Leu, Gly, Gin, Arg, Pro, Asp, He, Lys, or Thr. They also may be substituted on the N-terminus or on a side chain amino group as indicated above. If desired, S- or O-containing side chains of the PTH-rP hybrids of the invention may also be protected as disclosed above. Examples of preferred PTH-rP hybrids according to the invention are [Leu 8 , Gin 18 , Thr 33 , Ala 34 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Thr 33 , Ala 34 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gin 18 , Thr 33 , Ala 34 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gin 18 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Ala 19 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Gln 18 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gin 18 , Ala 19 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Ala 19 , Thr 33 , Ala 3 ]PTH and [Leu 8 , Asp 10 , Lys 11 , Gin 18 , Thr 33 , Ala 3 ]PTH. Preferred PTH-rP hybrids according to the invention are PTH(l-x') compounds wherein x' is an integer from 34 to 38, particularly 34, 36, 37 or 38 especially hPTH(l-x'), wherein one or more α-amino acids are replaced by the α-amino acid(s) present at the corresponding position in PTHrP preferably as indicated above. When the positions 33 and 34 are replaced by the corresponding α-amino acid sequence of PTHrP, the PTH compound is preferably a hPTH fragment comprising 34 α-amino acid units. PTH-rP hybrids with carboxy terminus are preferred. Preferably PTHrP is hPTHrP. The compounds of the invention may exist e.g. in free form, salt form or in the form of complexes thereof. Acid addition salts may be formed with e.g. organic acids, polymeric acids and inorganic acids. Such acid addition salt forms include e.g. the hydro- chlorides and the acetates. Complexes are e.g. formed from the compound of the invention on addition of inorganic substances, e.g. inorganic salts or hydroxides such as Ca- and Zn-salts, and/or an addition of polymeric organic substances. The present invention also provides a process for the production of the compounds of the invention. They may be prepared in a stepwise manner either in solution or using the solid phase synthesis process or genetic engineering. The compounds of the invention may be produced for example as follows: a) removing at least one protecting group which is present in a compound of the invention in protected form; or b) linking together by an amide bond two peptide fragments, the peptide fragments being such that the desired amino acid sequence of the desired compound is obtained, and then effec¬ ting optionally s.άge a) of the process, c) for the production of a PTH compound wherein the α-amino acid units in positions 1 and 2 at the amino terminus are replaced by a pseudo-dipeptide, reacting a pseudo-dipeptide in protected or unprotected form with a PTH peptide in protected or unprotected form in which the amino acid residues in positions 1 and 2 are omitted and if necessary carrying out process step a) ; or d) for the production of a PTH compound comprising at least one radical selected from D- or L-α-amino acid attached to the N-terminus and C2_ 6 alkoxycarbonyl and optionally substituted Ci-sal yl, C 2 -salkenyl, C 2 _ 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl attached to the terminal amino group and/or to a side chain amino group, introducing such a radical in a PTH compound in protected or unprotected form and free from such a radical, and if necessary carrying out process step a) ; and recovering the compounds thus obtained in free form, in salt form or in complex form. Process steps a) , b) and c) may be effected in analogy with known methods, e.g. as known in the art of peptide chemistry or as described in the following examples. Where desired, in these reactions, protecting groups which are suitable for use in peptides may be used for functional groups which do not parti¬ cipate in the reaction. The term protecting group may also inclu¬ de a polymer resin having functional groups. In process step b) , for the production of a PTH compound wherein the α-amino acid units in positions 1 and 2 at the amino terminus are replaced by a pseudo-dipeptide, one peptide fragment used as starting material may comprise the pseudo-dipeptide at its N-terminus. This starting material may be prepared in accordance with process step c) . In process step c) the pseudo-dipeptide used as starting material may be a compound of formula Ilaa or Ilbb ZZ'N - CHY - CW = CH - CHY' - COOH (Ilaa) ZZ'N - CY a Y b - CH 2 - NZ" - CHY' - COOH (Hbb) wherein Y, Y' , Y a , Y b , 1, Z' , Z" and W are as defined above, or a functional derivative thereof, e.g. ester, acid halide or a sy etric or asymetric anhydride. Compounds of formula Ilaa wherein W and Y' together with the moiety -C=CH-CH- to which they I I are attached, form an optionally substituted aromatic cyclic or heterocyclic residue, and compounds of formula Ilbb wherein Z" is alkyl or a protecting group, e.g. acetyl, or wherein -CY a Y b is C 3 _ 6 cycloalkyl and Z" is H are novel and form part of the invention. Process step d) may be carried out in analogy with known methods, e.g. alkylating methods. In a preferred embodiment of the invention, the alkylation is performed under reductive conditions, e.g. using a corresponding aldehyde or ketone. It may be performed for example in the presence of NaBH 3 CN, preferably at an acidic pH, e.g. from 5 to 7. The temperature of the reaction may be e.g. from -20° C to 100° C. It may be advantageous to carry out the reaction in an inert solvent, e.g. water, an alcohol, dioxane or DMF or a mixture thereof. A D- or L-α-amino acid may also be attached to the N-terminus in accordance with known procedure. The peptide fragment used as starting material in process step b) may comprise one or more unnatural amino acid units; it may also be substituted on the N-terminus and/or on a side chain amino group by a radical selected from C 2 - 6 lkoxycarbonyl, optionally substituted Cι_βalkyl, C 2 - 8 alkenyl, C2-s l nyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl or it may bear a D- or L-α-amino acid on the N-terminus. _> The compounds of the invention or fragments thereof comprising natural α-amino acid units may also be prepared using recombinant technology. According to a preferred embodiment of the invention there is also provided a process for the production of a medium-sized polypeptide, in which a fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide having the desired polypeptide linked to the C-terminal thereof, is expressed in bacterial cells. The gene 55 polypeptide may comprise the complete gp55 protein of bacteriophage T4 (188 amino acid residues) which is described in Gram, H. and Rϋger, R; 1985; The EMBO Journal, 4, (1), pp 257-264. Alternatively a fragment, preferably an N-terminal fragment of the gp55 protein may be used. For example, a gp55 protein fragment comprising the first 112 N-terminal amino acid residues of the protein may be used. Typically, however, the gene 55 polypeptide comprises at least the first 25 N-terminal residues of the gρ55 protein. The medium-sized polypeptide may be from about 20 up to 100, e.g. 150, preferably from about 20 to about 50, amino acids in length. Examples of medium-sized polypeptides include calcitonins, endorphins, gastric inhibitory peptide(s) , glucagon, neuropeptide Y, growth hormone releasing factor (GHRF) , amyloid β protein fragments, hirudin, insulin, somatostatin, epidermal growth factor, nerve growth factor and PTH or fragments thereof. Particularly preferred medium-sized polypeptide which may be prepared according to the process of the present invention are the compounds of the invention or fragments thereof having natural amino acid substitutions. Conveniently the gene 55-PTH fusion protein also comprises a cleavable linker between the gene 55 polypeptide and the desired polypeptide. Preferably the cleavable linker is chemically cleavable and more preferably contains the amino acid sequences Asp-Pro-Pro or Asn-Gly-Pro. In a further aspect the invention provides a nucleotide sequence coding for a fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide and a desired medium-sized polypeptide linked to the C-terminal thereof. The nucleotide sequence is preferably a DNA sequence suitable for expression in bacteria. The sequence typically contains nucleotides coding for a cleavable linker between the gene 55 and desired polypeptide coding sequences. The invention also provides a bacterial expression vector comprising a DNA sequence coding for the fusion protein. The expression vector typically contains, in addition to the fusion protein coding sequence, appropriate expression control sequences including a suitable promoter, an operator and a ribosome binding site and other appropriate regulatory sequences. Usually, also the expression vector contains one or more selectable markers. Any suitable promoter may be used, such as the TrpE, λPl, λPr, lac or Tac promoter. Preferably the promoter is the bacteriophage T7 promoter and the expression vector is a plasmid. For E. coli expression an RI or Col-El plasmid-derived vector may be used. For example, expression vector pET 17B, obtainable from Novagen, or similar expression vectors may be used. In another aspect the invention provides bacterial host cells transformed with a fusion protein coding sequence or an expression vector as described above. Any suitable bacterial host may be used, though preferably the host is E. coli. For example, E. coli strain BL21 (DE3) Lys E and similar strains may be used. Advantageously the fusion protein accumulates within the host cells in the form of insoluble inclusion bodies, and thereby facilitates recovery of the fusion protein product from the cells. In order to recover the desired polypeptide product from the fusion protein, the protein of the inclusion bodies is solubilised, and the desired polypeptide product cleaved from the fusion protein. Any suitable solubilisation treatment may be used, including acid treatment, e.g. at about pH 2 to 4, preferably with acid at about pH 2.5, or treatment with a denaturing agent, e.g. a mild denaturating agent such as guanidine hydrochloride . In addition it may be necessary to remove one or more unwanted N-terminal amino acid residues from the product which remain after cleavage. Thus in a further aspect the invention provides a process for the production of a desired medium-sized polypeptide, in a bacterial host, the process comprising: causing transformed bacterial host cells as defined above to express the fusion protein in the form of inclusion bodies; isolating the inclusion bodies; solubilizing the inclusion bodies, and cleaving the desired polypeptide from the fusion protein. In the case of some medium-sized polypeptides, such as the PTH compounds, it is not normally necessary to carry out carefully- controlled denaturation and renaturation procedures to obtain PTH products in active form, e.g. having PTH-like activity. The medium-sized polypeptide products may be obtained in active form merely by neutralising the acid conditions used for solubilisation. Solubilisation and cleavage of the fusion protein may be carried out in a single step. The invention also includes a fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide and, linked to the C-terminal thereof, a desired medium-sized polypeptide. Using the processes and vectors of the invention it has been found that it is possible to produce high levels of medium-sized polypeptides, particularly PTH products. In E. coli, we have found that up to about 50% of the total protein expressed is the desired fusion protein. Also, the fusion protein forms inclusion bodies which are easy to separate from the other material of the cells. Moreover the inclusion bodies often consist of at least about 90% of the desired fusion protein which can significantly reduce the amount of purification that is required. Further, expressing the PTH product, in the form of the fusion protein can substantially decrease endogenous processing of the polypeptide in the bacterial cell, allowing homogenous products to be obtained. Preferably the cleavable linker contains chemically cleavable amino acids adjacent the N-terminus .of the desired polypeptide, to permit the desired polypeptide to be cleaved from the fusion protein by simple chemical means. Preferably the desired polypeptide does not contain the chemically cleavable groups. Preferred chemically cleavable linkers contain the amino acids Asp-Pro-Pro or Asn-Gly-Pro. The Asp-Pro or Asn-Gly bonds may be chemically cleaved using acid conditions e.g. formic acid (normally about pH 2.5) or hydroxylamine respectively. The di- peptides Pro-Pro or Gly-Pro that remain on the N-terminus of the desired polypeptide may then be removed using a suitable dipeptidyl-peptidase. For example the L. lactis X-Pro dipeptidyl-peptidase EC 3.4.14.5 can be used. This peptidase is described in Nardi et al; 1991; Applied and Environmental Microbiology, 57, p45 to 50. The desired polypeptide may be purified following cleavage from the fusion protein. HPLC purification techniques may be used. Purification may be carried out before removal of any unwanted N-terminal amino acid residues. The process of the invention is further illustrated in the examples 306 to 312, which refer to sequences given in the accompanying Sequence Listing, in which SEQ ID No. 1 shows the amino acid sequence and corresponding DNA sequence of a truncated gp55-Asp-Pro-Pro-hPTH(l-38)OH fusion protein as cloned into the plasmid pET17B, and SEQ ID No. 3 shows the amino acid sequence and corresponding DNA sequence of a full length gp55-Asn-Gly-Pro- hPTH(l-38)OH fusion protein as cloned into the plasmid pET17B. In the following Examples all temperatures are in °C. The follo¬ wing abbreviations are employed: Tos = Tosyl DIPC = Diisopropylcarbodiimide Pmc = 2,2,5,7, 8-Pentamethylchroman-6-sulfonyl Ip = Isopropyl For = Formyl Cpe = 1-amino-cyclopentane-l-carboxylic acid Cpp = 1-amino-cyclopropane-l-carboxylic acid Cha = cyclohexylalanine tBu = t.butyl SEQ ID No. 11 shows the amino acid sequence of hPTH(l-34); SEQ ID No. 12 shows the amino acid sequence of hPTH(l-36); SEQ IQ No. 13 shows the amino acid sequence of hPTH(l-38). Examples 1, 2, 5, 6, 11, 20-24, 27-30, 36, 37, 40, 41, 47, 49, 51, 53, 54, 57, 58, 61, 76-80, 82, 179, 185, 187, 191-193, 226, 230, 237, 239, 256 and 289 are based on SEQ ID No. 11, the changed amino acid units and their position being indicated in the square brackets. Examples 12, 13, 18, 19, 31-35, 38, 39, 42-46, 48, 50, 52, 55, 59, 60, 62-71, 81, 83-85, 165-178, 180-184, 186, 188-190, 194-225, 227-229, 231-236, 238, 240-255, 257-266, 268-279, 282-288, 290-300 and 302-304 are based on SEQ ID No. 12, the changed amino acid units and their position being indicated in the square brackets. Examples 3, 4, 7-10, 14-17, 25, 26, 56, 72-75, 81, 86-164, 267, 280 and 281 are based on SEQ ID No. 13, th changed amino acid units and their position being indicated in the square brackets. EXB P E 1: M-Isopropyl hPTH(l-34) NH 2 This peptide is assembled in a stepwise manner on a poly-styrene- based resin support. The Boc-group is used for protection of the alpha amino-group and side-chain functional groups are protected as follows: Lys (2-chlorobenzyloxycarbonyl) , Ser(benzyl), Thr(benzyl), Glu(benzyl), Asp(benzyl), Met(O), His(DNP), Arg(Tos), and Trp(HCO) . Other residues are left unprotected. Amino-4-methylphenyl-methyl-co (polystyrene-divinylbenzene = MBHA- resin) (0,7 mmol/g) is subjected to the following cycle, steps (1) to (7), of treatments: (1) DCM (2) trifluoracetic acid (50 %) in DCM (3) DCM (4) diisopropylethyla ine (10 %) in DMF (5) DMF (6) preformed symmetrical anhydride (1.4 mmol per g starting resin) of Boc-amino acid in DMF (7) DMF Volumes of washes and reagents are from 5 to 20 ml per gram of starting resin. Each step is repeated as many times as necessary for either complete reaction of the resin (steps 2, 4, 6) or complete displacement of the previous reagent from the resin (steps 1, 3, 5, 7) . Samples of resin are removed after each cycle and checked for completeness of the coupling reaction by a colo- rimetric test for residual amino groups using ninhydrin. Symmetrical anhydrides of Boc-amino acids are prepared just prior to use by reacting Boc-amino acid (2,8 mmol per g resin) and DCCI (1,4 mmol per g resin) in DCM, containing DMFin amounts sufficient for complete dissolution of the Boc-amino acid. The mixture is filtered, more DMF is added to the filtrate which is concentrated by evaporation of the volatile components at a temperature not exceeding 15°C and the resulting solution is used in step (6) . The cycle of reactions, (1) to (7), is repeated for each amino acid residue such as to provide the sequence of the title compound except for Boc-Gln-OH and Boc-Arg(Tos) -OH, which are coupled in step (6) as their preformed 1-hydroxybenzo-triazole esters in DMF. The fully assembled peptide resin is treated twice with 20 ml of thiophenol 5% in DMF at r.t. for 1 hour and washed with DMF, methanol and dichloromethane. The peptide resin is again subjected to steps (1) to (5) followed by the addition of 0.5 ml of acetone, 84 mg of sodium cyanoborohydride and 0.2 ml of acetic acid in 20 ml of DMF per gram of resin. After 16 hours at RT the resin is washed with DMF and dichloromethane and dried. The peptide resin is treated with liquid HF, dimethyl sulfide, p-cresol and ethane-l,2-dithiol according to the 'low-high' procedure which is described, e.g., in International Journal of Peptide and Protein Research, vol.26, page 262-273 (1985) . After removal of the volatile components and washing with ethylacetate the residue is extracted with several portions of 1%-acetic acid, filtered and the filtrate liophilized. The lyophilized product is purified by repeated reversed-phase chromatography on a column of octadecyl-silica using a gradient of acetonitril in 2%-phosphoric acid or in 20 mM tetramethylammonium phosphate. Fractions contai¬ ning the pure compound are combined, filtered through a weakly basic ion-exchange resin in the acetate form and the filtrate lyophilized to give the title compound. MS (Ion-Spray) : 4160. EXAMPLE 2: [Lys ( -Isopropyl) 26 > 27 ]hPTH(l-34) NH? The peptide is assembled as described for Example 1 but using Lys(Fmoc) for incorporation in position 13 and Fmoc-Ser(tBu) in terminal position 1. The fully assembled peptide resin is treated twice with 20 ml of thiophenol 5% in DMF at r.t. for 1 hour and washed with DMF, methanol and dichloromethane. The dry resin is treated with liσuid HF as described for Example 1. The cleavage product (350 mg) is suspended in a mixture of methanol (5 ml), phosphate buffer pH = 5.0 (5 ml), sodium cyanoborohydride (48 mg) and acetone (0.28 ml). After 16 hours at RT the reaction mixture is filtered and the filtrate evaporated. The residue is suspended in 20%-piperidine in DMF for 15 minutes, diluted with 20 volumes of ether and filtered. The residue is dissolved in 100 ml of water and acetic acid added to pH = 3, filtered and the filtrate lyophilized. The lyophilizate is purified by reversed-phase chromatography on a column of octa¬ decyl-silica using a gradient of acetonitril in 2%-phosphoric acid. Fractions containing the pure compound are combined, filte¬ red through a weakly basic ion-exchange resin in the acetate form and the filtrate lyophilized to give the title compound. MS (Ion Spray) : 4205.6. EXAMPLE 3: N£-Isoproρyl [Lys (N -Isopropyl) 13 26 > 27 ]hPTH-(l-38)-OH a) Solid phase peptide synthesis The peptide is synthesized in a stepwise manner on a polystyrene based resin support. The alpha-a ino group is protected by Fmoc and the side-chain functional groups as followed: Asp(OtBu), Glu(OtBu), His(Trt), Lys(Boc), Asn(Trt), Gln(Trt), Arg(Pmc) and Ser(tBu). Other amino acids are left unprotected. Fmoc-Gly esterified to 4-Hydroxymethyl-ρhenoxymethyl- co(polystyrene-l%-divinylbenzene) , 0.5 mmol/g, is used as starting material for the stepwise solid phase synthesis, which consists of repetitive cycles of alpha-amino deprotection, washing, coupling (attachment of new amino acid) and washing. A three to five fold excess of Fmoc-amino acids is coupled as preformed HOBt-esters using DIPC. Fmoc-Arg(Pmc) , Fmoc-Asn(Trt) and Fmoc-Gln(Trt) are coupled as symmetrical anhydrides using DIPC. After complete assembly of the peptide chain the Fmoc-protecting group of Ser 1 is removed by 20% piperidine/DMF. Cleavage of the peptide from the polystyrene resin and removal of all side chain protecting groups is obtained by treatment of the peptide resin with a mixture of 10% ethanedithiol, thioanisole, thiocresole and water in 90% TFA for three hours at room temperature. The resin particles are filtered off and washed with some TFA. The product is precipitated from the combined filtrates by addition of ether, filtered and dried. The product is purified by chromatography on a C-18 silica column using a gradient of acetonitrile in 2% H 3 P0 4 /water. Fractions containing the pure compound are collected, filtered through an anion-exchange resin (Biorad, AG 4-X4, 100-200mesh acetate form) and lyophilized to give hPTH-(l-38) -OH. b) Alkylation 40 mg (9 μ ol) hPTH-(l-38) -OH(4458.2 g/mol) are dissolved in 1.2 ml methanol, 1.2 ml phosphate buffer (Merck no. 9887 adjusted to pH 5.0), 45 mg (716 mmol) NaBH 3 CN (62.84 g/mol) and 0.8 ml (11 mmol) acetone (73.52 ml/mol) . The reaction is monitored by RP-HPLC on a C-18 silica column and finished after 15 hours at room temperature. The reaction mixture is diluted with water and chromatographied on a C-18 silica column using a gradient of acetonitrile in 2% H 3 PO 4 /water. Fractions containing the pure compound are collected, filtered through an anion-exchange resin (acetate form) and lyophilized to give the title compound as polyacetate, polyhydrate. [α] 20 = - 5.7° (c = 0.317 in 95 % AcOH) D MS (Ion-Spray) : 4626 EXAMPLE 4: NSL-Methyl [Ala 1 ]PTH-(1-38)-OH The peptide chain is assembled in the same manner as in example 3a. At position 1 instead of Fmoc-Ser(tBu) -OH the unnatural amino acid Fmoc-N α -Methyl-Ala-OH is coupled to the peptide resin. Cleavage, deprotection and purification is performed as in example 3a. MS (Ion Spray) = 4455,91 EXAMPLE 5: [Ala 1 ,Ala 3 ,Leu 8 ,Gin 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Phe 23 ,His 25 , His 26 ,Leu 27 ,Thr 33 ,Ala 3 ]hPTH(l-34)OH This peptide is prepared in analogy with the procedure of Example 3a. Instead of Fmoc-Gly esterified to 4-hydroxymethyl-phenoxy- methyl-co(polystyrene-divinylbenzene) the appropriate Fmoc-amino acid, e.g. Fmoc-Ala, Fmoc-Phe, Fmoc-D-Ala, Fmoc-D-Phe, etc. is used. Additionally the side-chain functional groups are protected as follows: Thr(t.-butyl) , Trp(Boc) and Tyr(t.-butyl) . By repeating the procedure disclosed in Examples 3 and 5 but using the appropriate starting materials, the following compounds may be obtained: [Leu 8 ,Asp 10 ,Ala 16 ,Gln 18 ,Thr 33 ]hPTH(l-34)0H [Ile 1 ]hPTH(l-38)OH (IS-MS: 4484) [Ala^ bu^hPTHd-SδJOH (IS-MS: 4428) [Ala 1 ,Nva ]hPTH(l-38)OH (IS-MS: 4442) [Ala 1 ,Ile 2 ]hPTH(l-38)OH (IS-MS: 4456) EXAMPLE 11: [Ala 1 ,Ala 3 ,Leu 8 ,Gin 13 , la 16 ,Gin 18 ,Ala 19 ,His 26 ,Leu 27 , Thr 33 ,Ala 34 ]hPTH(l-34)OH [N-MeAlaMhPTHd-SδJOH (IS-MS: 4286) [Ala 1 ,Ala 3 ,Leu 8 ,Gln 18 ]hPTH(l-36)OH (IS-MS: 4235) [Thr -hPTH-U-SβJOH (IS-MS: 4472) [Leu^-hPTH-d-SδJOH (IS-MS: 4484) [Abu^-hPTH-d-SδJOH (IS-MS: 4456) [Gaba 1 ]-hPTH-(1-38)OH (IS-MS: 4456) [Leu 8 ,Lys 11 ,Gln 18 ]hPTH(l-36)OH ;Leu 8 ,Gln 16 ,Asp 17 ,Leu 18 ,Arg 1 ,Arg 22 ]hPTH(l-36)OH (IS-MS: 4347) [Leu 8 ,Gln 18 ,Thr 33 ,Ala 34 ]-hPTH(l-34)0H (IS-MS: 4007) [Leu 8 ,Ala 1 -,Gin 18 ,Ala 19 ,Thr 33 ,Ala 3 ]hPTH(1-34)OH (IS-MS: 3906) [Leu 8 ,Ala 13 ,Gin 18 ,Gin 26 ,Phe 27 ,Thr 33 , Ala 3 ]hPTH(l-34)OH Ip-[Leu 8 ,Lysdp) - -,Gin 18 ,Lys(Ip) 26 - ~ 7 ,Thr 33 , Ala 34 ]hPTH(l-34)OH (IS-MS: 4175) Ip-[ eu 8 ,Ala 13 ,Gin 18 ,Gin 26 ,Phe 27 ,Thr 33 , Ala 3 ]hPTH(l-34)OH [Gln 16 ]hPTH(l-38)OH [Ser 14 ]hPTH(l-38)OH [Ala 1 ,Ala 3 ,Leu 8 ,Gln 13 ,Ala 16 ,Gln 18 ,Ala 19 ,His 25 ,His 26 , Leu 27 ,Thr 33 ,Ala 34 ]hPTH(1-34)OH [Ala 1 , la 3 ,Leu 8 ,Gin 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Gin 26 ,Phe 27 , Thr 33 ,Ala 34 ]hPTH(l-34)OH [Leu 8 ,Ala 16 ,Gln 18 ,Thr 33 ,Ala 34 ]hPTH(l-34)OH (IS-MS: 3965) [Leu 8 ,Gin 18 , la 29 ,Glu 30 ,lie 31 ]hPTH(1-34)OH EXAMPLE 31 [Leu 8 , sp 10 ,Lys 11 ,Gin 18 ]hPTH(1-36)OH EXAMPLE 32 [Leu 8 , sp 10 ,Lys 11 ,Ser 14 ,He 15 ,Gin 16 ,Asp 17 ,Leu 18 , Arg 1 ]hPTH(l-36)OH EXAMPLE 33: [Leu 8 ,Asp 10 ,Lys 11 ,Leu 18 ]hPTH(l-36)OH EXAMPLE 34: [Leu 8 ,Gin 16 ,Asp 17 ,Leu 18 , rg 19 ]hPTH(1-36)OH EXAMPLE 35: [Leu 8 ,Asp 10 ,Lys 11 ,Ala 17 ,Leu 18 ]hPTH(l-36)0H (IS-MS: 4252) EXAMPLE 36: [Leu 8 ,Gin 16 ,Asp 17 ,Leu 18 ,Arg 19 ,Thr 33 ,Ala 34 ] hPTH(l-34)OH EXAMPLE 37: [Leu 8 , sp 10 ,Lys 11 ,Gin 18 ,Thr 33 ,Ala 34 ]hPTH(1-34)OH (IS-MS: 4022) EXAMPLE 38: [Leu 8 , la 16 ,Asp 17 , eu 18 ,Ala 19 ]hPTH(1-36)OH EXAMPLE 39: [Leu 8 ,Asp 10 , la 16 , sp 17 ,Leu 18 ,Ala 19 ]hPTH(1-36)OH EXAMPLE 40: [Leu 8 ,Gin 18 ,Arg 2 ,Thr 33 ,Ala 3 ]hPTH (1-34)OH EXAMPLE 41: [Leu 8 ,Asp 10 ,Lys 11 ,Gin 16 ,Asp 17 ,Leu 18 ,Arg 1 ,Thr 33 , Ala 3 ]hPTH(l-34)OH (IS-MS: 4077) EXAMPLE 42: [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ,Ala 19 ]hPTH(1-36)OH (IS-MS: 4181) EXAMPLE 43: [Leu 8 ,Ala 16 ,Asp 17 ,Gin 18 ,Ala 19 ]hPTH(1-36)OH (IS-MS: 4193) EXAMPLE 44: [Leu 8 ,Ala 16 ,Ala 17 ,Gln 18 ,Ala 19 ]hPTH(l-36)OH US-MS: 4149) EXAMPLE 45: [Leu 8 ,Ala 17 ,Gin 18 ,Ala 19 ]hPTH(1-36)OH EXAMPLE 46: [Leu 8 ,Ala 17 ,Gin 18 ,Ala 19 ,Arg 22 ]hPTH(l-36)OH (IS-MS: 4219) EXAMPLE 47: [Leu 8 ,Ala 17 ,Gin 18 ,Ala 19 ,Arg 22 ,Thr 33 ,Ala 34 ] hPTH(l-34)OH (IS-MS: 3960) EXAMPLE 48: [Leu 8 ,Gln 18 ]hPTH(1-36)OH EXAMPLE 49: [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ,Thr 33 ,Ala 34 ] hPTH(l-34)OH (IS-MS: 3980) EXAMPLE 50: [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ]hPTH(1-36)OH (IS-MS: 4240) EXAMPLE 51: [Leu 8 ,Asp 10 ,Lys 11 , la 16 ,Gin 18 ,Ala 19 ,Thr 33 ,Ala 34 ] hPTH(l-34)OH (IS-MS: 3923) EXAMPLE 52: [Leu 8 ,Asp 10 , la 16 ,Gin 18 ]hPTH (1-36)OH (IS-MS: 4225) EXAMPLE 53: [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ,Ala 19 ,Thr 33 ] hPTH(l-34)OH (IS-MS: 3999) [Leu 8 ,Gin 13 , la 16 ,Gin 18 ,Ala 19 ,His 26 ,Leu 27 ,Thr 33 ] hPTH(l-34)0H [Leu 8 ,Ala 16 ,Gin 18 ,Ala 19 ,Arg 22 ]hPTH(1-36)OH [Ile 15 ]hPTH(l-38)OH [Leu 8 ,Gln 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Arg 22 ,His 26 ,Leu 27 , Thr 33 ,Ala 34 ]hPTH(l-34)OH [Leu 8 ,Gin 13 ,Ala 1 -,Gin 18 ,Arg 19 ,His 26 ,Leu 27 ,Thr 33 , Ala 3 ]hPTH(l-34)OH [Leu 8 ,Ser 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Arg 22 ]hPTH(1-36)OH [Leu 8 ,Ala 13 ,Ala 16 ,Gin 18 ,Ala 19 , rg 26 ,Arg 27 ] hPTH(l-36)OH [Leu 8 ,Gin 13 ,Ala 1 - ,Gin 18 ,Ala 1 - ,His 2 -,Leu 27 ,Arg 33 , Ala 34 ]hPTH(l-34)OH [Leu 8 ,Ala 16 ' 17 ' 18 - 19 ]hPTH(l-36)OH [Leu 8 , la 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Gin 26 ,Phe 27 ] hPTH(l-36)OH (IS-MS: 4127) Ip-[Leu 8 ,Ala 13 ,Ala 16 ,Gln 18 ,Ala 19 ,Gln 26 ,Phe 27 ] hPTH(l-36)OH Ip- [Leu 8 ,Lys (Ip) 13 ,Ala 16 ,Gin 18 ,Ala 19 , Lys(Ip) 26 ' 27 ]hPTH(l-36)OH [Leu 8 ,Ala 16 ,Gln 18 ,Ala 19 ]hPTH(l-36)OH (IS-MS: 4166) Ip-[Leu 8 ,Lys (Ip) 13 ,Ala 16 ,Ala 17 ,Ala 18 ,Ala 19 , Lys(Ip) 26 ' 27 ]hPTH(l-36)OH [Aib 3 ,Gln 18 ]hPTH(l-36)OH (IS-MS: 4283) Ip-[Leu 8 ,Asp 10 ,Lys dp) 11 ' 13 ' 26 ' 27 ,Gin 18 ] hPTH(l-36)OH Ip- [Leu 8 ,Ser 13 ,Ala 16 ,Gin 18 ,Ala 19 ,Arg 22 , Lys(Iρ) 26 ' 27 ]hPTH(l-36)OH [Leu 8 ,Tyr 18 ]hPTH(1-36)OH [Ser 33 ]-hPTH-(l-38)-OH [Thr 33 ]-hPTH-(l-38)-OH [Leu 33 ]-hPTH-(l-38)-0H [Gly 33 ]-hPTH-(l-38)-OH [Leu 8 ,His 10 ,Gin 18 ,Arg 22 ,Thr 33 ,Ala 34 ]hPTH(1-34) OH [Leu 8 ,Gly 10 ,Gin 18 , rg 22 ,Thr 33 ,Ala 3 ] PTH(1-34)OH [Leu 8 ,Glu 10 ,Gln 18 ,Arg 22 ,Thr 33 ,Ala 3 ]hPTH(l-34)OH [Leu 8 ,Thr 10 ,Gin 18 ,Arg 22 ,Thr 33 ,Ala 34 ]hPTH(1-34)OH [Leu 8 ,Gln 10 ,Gln 18 ,Arg 22 ,Thr 33 ,Ala 34 ]hPTH(l-34)OH [Gln 33 ]-hPTH-(l-38)-OH [Leu 8 ,Tyr 10 ,Gin 18 ,Arg 22 ,Thr 33 ,Ala 34 ]hPTH(1-34)OH [1-amino-cyclopentane-l-carboxylic acid 1 ,Leu 8 , la 16 ,Gin 18 , Ala 19 ]hPTH(l-36)OH [1-amino-cyclopentane-l-carboxylic acid 1 ,Leu 8 , Ala 13 ' 16 ,Gln 18 ,Ala 19 ,Arg 6 ' 27 ]hPTH(l-36)OH [1-amino-cyclopentane-l-carboxylic acid 3 ,Gin 18 ] hPTH(l-36)OH (IS-MS: 4309) [Arg 12 -OH [Ser 12 -OH [Cys 13 -OH [He 13 -OH [Asn 13 -OH [Trp 13 -OH [Asp 13 -OH [Val 13 -OH [Thr 13 -OH [Ser 13 -OH [Tyr 13 -OH [Met 13 -OH [Gin 13 -OH [Leu 13 -OH [Ala 13 -OH [Gly 13 -OH [Val 14 -OH [Ala 14 -OH [Lys 14 -OH [Arg 14 -OH [Thr 14 -OH [He 14 -OH - 40 Pro 3 ,Thr 33 ]-hPTH-(l-38) -OH [Arg 33 hPTH-(l-38)-OH Pro 33 ■ hPTH -38)-OH [Asp 33 ■ hPTH -38)-OH He 33 •hPTH -38)-OH Lys 33 τ-hPTH-d-38)-OH lie 31 ,Arg 33 ]-hPTH-(1-38) -OH EXAMPLE 165: 1-aminocyclopentane-l-carboxylic acid 1 ]hPTH- 1-36)NH? The peptide is assembled in a stepwise manner on a polystyrene based resin support. The Fmoc-group is used for protection of the alpha-amino groups. Side-chain functional groups are protected as Arg(Pmc), Asn(Trt), Asp(OtBu), Gln(Trt), Glu(OtBu), His(Trt), Lys(Boc), Ser(tBu), Thr(tBu) ,Trp(Boc) and Tyr(tBu). Other amino acids are left unprotected. 4-(2' , . '-Dimethoxyphenyl-Fmoc-amino-methyl) -phenoxy-co (polystyre- ne-divinylbenzene) , 0.4 mmol/g, which may be prepared, e.g., as described in Tetrah. Letters, 28, 3787-3790 (1987) is subjected to the following cycle, steps (1) to (5), of treatments: (1) DMF (2) piperidine (20%) in DMF (3) DMF (4) mixture of HOBt, diisopropylcarbodiimide, and Fmoc-ala nine (0.8 mmol per gram starting resin each) (5) DMF Volumes of washes and reagents are from 5 to 20 mL per gram of starting resin. In the next cycle of treatments (1) to (5), Fmoc-valine j.s subs¬ tituted for Fmoc-alanine and so on for each cycle such as to as¬ semble on the resin the correct amino acid sequence of the title compound. Each step is repeated as many times as necessary for either com¬ plete reaction of the resin (steps 2, 4) or complete displacement of the previous reagent (s) from the resin (steps 3, 5). Samples of the resin are removed after each cycle and checked for comple¬ teness of the coupling reaction by a colorimetric test for resi¬ dual amino groups using ninhydrin. At the end of the synthesis a final cycle comprising steps (1) to (3) only is performed and the peptide resin is washed with 2-pro- panol, then with a mixture of methanol and methylene chloride (1:1 v/v) and dried throughly in a vacuum desiccator. The peptide resin (1 g) is suspended in a mixture (20 ml) of trifluoroacetic acid, water, and 1,2-ethanedithiol (90:5:5 v/v) for 2 hours at room temperature, the resin particles are filtered off and washed with a small volume of TFA. The product is preci¬ pitated from the combined filtrates by addition of ether (20 vo¬ lumes), filtered, washed with more ether and dried. The residue is dissolved in 2 % acetic acid, the solution let to stand at r.t. for 8 hours prior to lyophilization. The lyophilisate is chromatographed on a C-18 silica column using a gradient of acetonitrile in 2% H 3 P0 . Fractions are checked by analytical HPLC and those containing the pure compound are collected, fil¬ tered through an anion-exchange resin in the acetate form and lyophilised to give the title compound as a polyacetate, polyhydrate. Fmoc-1-aminocyclopentane-l-carboxylic acid used in the prepara¬ tion of the peptide resin intermediate may be prepared, e.g. as described by G. Valle et al.,1988, in Can.J.Chem.66:2575-2582. MS (Ion-Spray) : 4312 EXAMPLE 166: [1-(1— minocyclopropane-1-carbo∑ylic acid)]hPTH- (1-36)NH 2 This peptide is prepared in analogy with the procedure of Example 165. Fmoc-1-aminocyclopropane-l-carboxylic acid used in the preparation of the peptide resin intermediate may be prepared, e.g., as described by M. Crisma et al. (1989) in Int.J.Biol.Macromol.11:345-352. MS (Ion-Spray) : 4283 By repeating the procedure as disclosed in Example 165 but using the appropriate starting materials, following compounds may be obtained: [D-Pro 1 ] hPTH ( l-36) NH 2 [Nva 1 ] hPTH ( l-36) NH 2 [N-Me-Ser 1 ] hPTH ( l-36 ) NH 2 [Indole-2-carboxylic acid 1 ]hPTH(1-36)NH 2 [Indole-3-carboxylic acid 1 ]hPTH(1-36)NH 2 [Pyridine-3-carboxylic acid 1 ]hPTH(1-36)NH 2 [Pyridine-2-carboxylic acid 1 ]hPTH(1-36) H 2 [Hexahydropyridazine-3-carboxylic acid 1 ]hPTH(1-36)NH 2 [Morpholine-2-carboxylic acid 1 ]hPTH(l-36)NH 2 [Pro 1 ]hPTH(1-36)NH 2 [Leu 1 ]hPTH(1-36) H 2 [Ile 1 ]hPTH(l-36)NH 2 [Thr 33 ,Ala 3 ]hPTH(1-34)NH 2 [Nva 8 ]hPTH(l-36)NH 2 [Gin 18 ]hPTH(1-36)NH 2 [Tyr 18 ]hPTH(l-36)NH 2 [Lys 18 ]hPTH(l-36)NH 2 [Ala 18 ]hPTH(1-36)NH 2 [Phe 23 ,His 25 ,His 2 -,Leu 27 ]-hPTH(1-34)NH 2 [Phe 23 ]-hPTH(l-36)NH 2 (IS-MS: 4247) [Phe 23 ,His 25 ,His 26 ,Leu 27 ,He 28 ,Ala 29 ,Glu 30 ,He 31 , Thr 33 ,Ala 34 ]-hPTH(1-34)NH 2 (IS-MS:3934) [Ala 29 ]-hPTH(l-36)NH 2 (IS-MS: 4248) [Ala 3 ]-hPTH(l-36)NH 2 (IS-MS: 4210) [Gln 25 ]hPTH(l-36)NH 2 [Leu 8 ,Asp 10 ,Lys 11 ,Thr 33 ,Ala 34 ]hPTH(1-34)NH 2 [Ala 1 ,His 5 ,Leu 8 ,Asp 10 ,Lys 11 ,Thr 33 ,Ala 34 ] hPTH(l-34)NH 2 EXAMPLE 193: [Ser 1 ,Ile 15 ,Gln 16 ,Asp 1 ,Leu 18 ,Arg 19 ,Thr 33 ,Ala 34 ] hPTH(l-34)NH 2 EXAMPLE 194 [D-Phe 34 , D-Ala 36 ]hPTH(l-36)-NH 2 [MS (IS): 4290] EXAMPLE 195 [Ala 3 ]hPTH(l-36)NH 2 [MS(IS):4271 ] EXAMPLE 196 [D-Ser 3 ]hPTH(l-36)NH 2 [MS (IS) :4290] [D-Glu ]hPTH(l-36)NH 2 [MS (IS) :4290] [D-His 9 ]hPTH(l-36)NH 2 [MS (IS) :4286] [Ala 10 ]hPTH(l-36)NH 2 [MS(IS) :4243] [D-Asn 10 ]hPTH(l-36)NH 2 [MS(IS): 4288] [Ala 1 ]hPTH(l-36)NH 2 [MS (IS): 4299] [Gln 13 ]hPTH(l-36)NH 2 [MS (IS) 4287] [His 13 ]hPTH(l-36)NH 2 [MS (IS) 4296] [Leu 13 ]hPTH(l-36)NH 2 [MS (IS) 4371] [Ala 13 ]hPTH(l-36)NH 2 [MS (IS) 4228] [Ala 13 ,Gin 26 ,Phe 27 ,D-Phe 34 ,D-Ala 36 ]hPTH(1-36)NH 2 [MS (IS) : 4249] [Ala 1 ]hPTH(l-36)NH 2 [MS (IS): 4219] [D-His 1 ]hPTH(l-36)NH 2 [MS(IS): 4288] [D-Asn 16 ]hPTH(l-36)NH 2 [MS (IS): 4284] [Ala 17 hPTH(l-36)NH 2 [MS (IS): 4270] [D-Ser 17 ]hPTH(l-36)NH 2 [MS (IS): 4288] [Ala 19 ]hPTH(l-36)NH 2 [MS (IS): 4228] [D-Glu 19 ]hPTH(l-36)NH 2 [MS (IS) 4288] [Ala 21 ]hPTH(l-36)NH 2 [MS (IS): 4257] [Ala 22 ]hPTH(l-36)NH 2 [MS (IS): 4227] [Gin 26 ]hPTH(1-36)NH 2 [MS (IS) 4287] [Nle 6 ]hPTH(1-36)NH 2 [MS (IS) 4271] [D-Lys 26 ]hPTH(l-36)NH 2 [MS(IS) : 4288] [Nle 8 ' 18 < 27 ]hPTH(l-36)NH 2 [His 27 ]hPTH(l-36)NH 2 [MS (IS) :4294] [Phe 2 ]hPTH(l-36)NH 2 [MS (IS): 4304] [Nle 27 ]hPTH(1-36)NH 2 [MS (IS): 4271] [Asn 2 ]hPTH(1-36)NH 2 [MS (IS): 4271] [Ala 27 ]hPTH(1-36)NH 2 [MS (IS): 4228] [D-Gln 29 ]hPTH(l-36)NH 2 [MS(IS): 4289] [D-Asp 30 ]hPTH(l-34)NH 2 [MS(IS): 4118] [Ala 30 ]hPTH(1-36)NH 2 [MS (IS): 4241] [D-Val 31 ]hPTH(1-36)NH 2 [MS (IS): 4290] [Ala 31 ]hPTH(l-36)NH 2 [MS (IS): 4258] [Lys 32 ]hPTH(l-34)NH 2 [MS (IS): 3832] [D-His 3 ]hPTH(l-36)NH 2 [MS (IS) : 4288] [Ala 3 ]hPTH(1-36)NH 2 [MS (IS): 4219] [D-Asn 33 ]hPTH(l-36)NH 2 [MS (IS): 4288] [Ala 33 ]hPTH(l-36)NH 2 [MS (IS): 4210] [NMePhe 3 ]hPTH(l-36)NH 2 [MS (IS): 4301] [D-Asp 30 ]hPTH(l-36)NH 2 [ MS (IS): 4290] Ip-[Nle 8 , 18 ,Lys (Ip) 13 ' 26 < 27 ,D-Asn 33 ,D-Phe 34 ] hPTH(l-34)NH 2 Ip-[Nle 8 ' 18 ' 27 ,Lys(Ip) 13 ' 26 ]hPTH(l-36)NH 2 [Nle 8 J 8 ,D-Asn 33 ,D-Phe 3 ]hPTH(1-34)NH 2 [MS (IS) : 4080] [Lys(Ip) 13 ]hPTH(l-36)NH 2 [MS(IS): 4331] Propargyl-[A 1 ]-hPTH-(1-36)-NH 2 [Ala 0 ]-hPTH-(1-36)-NH 2 [Pro°]-hPTH-(l-36)-NH 2 Acetyl-hPTH-(1-36)-NH 2 [HyPro 1 ]-hPTH-(1-36) -NH 2 N-Dimethyl-[Ala 1 ]-hPTH-(1-36)-NH 2 [D-Ser 1 ]-hPTH-(1-36)-NH 2 [MS(IS): 4288] [Lys (For) -]-hPTH-(1-36) -NH 2 [MS (IS): 4356] [D-Glyceric acid 1 ]-hPTH-(1-36)-NH 2 [Asn 1 ]-hPTH-(1-36)-NH 2 [4-Aminobenzoic acid 1 ]-hPTH-(1-36)-NH 2 [4-Aminosalicylic acid 1 ]-hPTH-(1-36)-NH 2 [TMSA 1 ]-hPTH-(1-36) -NH 2 [MS (IS): 4343] [Phe 1 ]-hPTH-(1-36) -NH 2 [Propargylglycin 1 ]-hPTH-(1-36)-NH 2 [Ala 1 ,His 5 ,Leu 8 ,Asp 10 ,Lys 11 ,Gin 18 ,Phe 22 ,Phe 23 ,His 25 ,His 26 , Leu 27 ,Thr 33 ,Ala 34 ]-hPTH-(l-34)-NH 2 EXAMPLE 257 [Abu 2 ]-hPTH-(1-36) -NH 2 EXAMPLE 258 [D-Val 2 ] -hPTH- ( 1-36) -NH 2 [MS ( IS) : 4288 ] EXAMPLE 259 [tert . Leu 2 ] -hPTH- ( 1-36) -NH 2 EXAMPLE 260 [Ala 1 ] -hPTH- ( 1-36) -NH 2 EXAMPLE 261: [D-Ile 5 ]-hPTH-(l-36) -NH 2 [MS (IS): 4288] EXAMPLE 262: [D-Gln 6 ]-hPTH-(1-36) -NH 2 [MS (IS): 4288] EXAMPLE 263: [D-Leu 7 ]-hPTH-(1-36) -NH 2 [MS (IS): 4288] EXAMPLE 264: [Nle 8 ]-hPTH-(1-36) -NH 2 [MS (IS): 4268] EXAMPLE 265: [Phe 8 ]-hPTH-(1-36) -NH 2 [MS (IS): 4303] EXAMPLE 266: [Cha 8 ]-hPTH-(1-36)-NH 2 [MS(IS): 4309] EXAMPLE 267: [Leu 8 ]-hPTH-(1-38) -NH 2 EXAMPLE 268: [D-Leu 11 ]-hPTH-(1-36) -NH 2 [MS(IS): 4287] EXAMPLE 269: [Ala 11 ]-hPTH-(1-36) -NH 2 [MS (IS): 4244] EXAMPLE 270: [D-Lys 13 ]-hPTH-(1-36)-NH 2 [MS(IS): 4288] EXAMPLE 271: [D-Leu 15 ]-hPTH-(1-36) -NH 2 [MS (IS): 4288] EXAMPLE 272: [Ala 15 ]-hPTH-(1-36)-NH 2 [MS (IS): 4243] EXAMPLE 273: [Ala 16 ]-hPTH-(1-36)-NH 2 [MS(IS): 4243] EXAMPLE 274: [Met(0 2 ) 18 ]-hPTH-(1-36)-NH 2 [MS(IS): 4320] EXAMPLE 275: [Nle 18 ]-hPTH-(l-36) -NH 2 [MS (IS): 4268] EXAMPLE 276: [D-Met 18 ]-hPTH-(l-36)-NH 2 [MS(IS): 4288] EXAMPLE 277: [Lys 20 ]-hPTH-(1-36)-NH 2 [MS(IS): 4259] EXAMPLE 278: [D-Arg 20 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 279: [D-Val 21 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 280: [Trp(S0 2 Pmc) 23 ]-hPTH-(1-38)-NH 2 [MS (IS): 4723] EXAMPLE 281: [Trp(Pmc) 23 ]-hPTH-(1-38)-NH 2 [MS (IS): 4660] EXAMPLE 282: [D-Trp 23 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 283: [Ala 23 ]-hPTH-(1-36)-NH 2 [MS(IS): 4171] EXAMPLE 284: [D-Leu 2 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 285: [Phe 25 ]-hPTH-(l-36) -NH 2 [MS(IS): 4277] EXAMPLE 286: [Lys 25 ]-hPTH-(1-36) -NH 2 [MS(IS): 4258] EXAMPLE 287: [Ala 25 ]-hPTH-(1-36)-NH 2 [MS (IS): 4201] EXAMPLE 288: [Ala 26 ]-hPTH-(1-36) -NH 2 [MS (IS): 4229] EXAMPLE 289: [Lys 26/2 (For) ]-hPTH-(1-34)-NH 2 EXAMPLE 290: [D-Lys 7 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 291: [D-Leu 28 ]-hPTH-(1-36) -NH [MS (IS): 4288] EXAMPLE 292: [D-Phe 3 ]-hPTH-(1-36)-NH 2 [MS (IS): 4288] EXAMPLE 293: [D-Val 35 ]-hPTH-(1-36)-NH 2 EXAMPLE 294: [Ala 35 ]-hPTH-(1-36) -NH 2 EXAMPLE 295 [Pro 35 ]-hPTH- (1-36)-NH 2 EXAMPLE 296 [NMeVal 35 ]-hPTH-(l-36)-NH 2 EXAMPLE 297 [Thr 35 ,Ala 36 ]-hPTH-(l-36)-NH 2 EXAMPLE 298 [D-Ala 36 ]-hPTH-(1-36)-NH 2 EXAMPLE 299 [NMeAla 36 ]-hPTH-(1-36) -NH 2 EXAMPLE 300: (5-Amino-4-fluoro-2-isopropyl)-hex-3-enoyl-hPTH(3- 36)NH 2 a) Preparation of hPTH-(3-36)-NH-resin This intermediate is prepared in analogy with the procedure of Example 165. b) [ (5-Amino-4-fluoro-2-isopropyl)-hex-3-enoyl]hPTH(3-36) -amide 204.6 mg Fmoc-hPTH(3-36)-NH-resin obtained in a) above are treated with DMF for 5 min. and then washed several times with isopropanol and DMF. The Fmoc-protecting group is removed by treatment with DMF/piperidin 8:2 for 10 min.. The deprotected PTH-fragment, 38.1 mg of 4-fluoro-2-isopropyl-5-t.-butoxycarbo- nylamino-hex-3-enoic acid, 68.7 mg benzotriazol-1-yloxytris (pyr- rolidino)ρhosphonium hexafluorophosphate (PyBOP) and 26.6 mg 4-methylmorpholin are shaken for 80 min. in 0.7 ml DMF. After several washings with isopropanol and DMF, the solid residue is treated with 4.5 ml TFA/0.25 ml water/0.25 ml ethanedithiol for 55 min. This mixture is then filtered and by addition of diethyl ether the title compound precipitated from the remaining solu¬ tion. The title compound is purified by prep. HPLC (Vydac column, gradient A = water, B = 7 acetonitril/3 water/0.2 phosphoric acid) : MS (Ion-spray) : mass 4272 [ α ] Hg = -66,8° (c=0.25 in 95% AcOH) 365 n EXAMPLE 301: 4-Fluoro-2-isopropyl-5-tert.butoxycarbonylamiιιo-hex- 3-enoate a) (S)-3-(1-Oxo (4-fluoro-3-hydroxy-2-isoρropyl)hex-4-enyl) -4- ρhenylmethyl-2-oxazolidinone The title compound is prepared analogous to the procedure described by D.A. Evans et al., Org. Synth. _68, 1990; starting from (S)-3-(l-oxoisobutyl)-4-phenylmethyl-2-oxazolidinone and 2- fluoro-but-2-enal. MS (FAB) : MH + 350 b) (S)-3-(l-Oxo(4-fluoro-3-Q-(2,2,2trichlorethanimino)-2- isopropyl)hex-4-enyl)-4-phenylmethyl-2-oxazolidinone 1.5 g of the compound of Example 301a) are dissolved in 6 ml DCM. At 0° 0.0958 ml 1,8-diazabicyclo(5,4,0)undec-7-en (DBU) are added. To this solution 0.475 ml trichloroacetonitril in 2 ml DCM is added dropwise at 0°. After 1 hour the reaction mixture is evaporated and the residue is purified by column chromatography on silica gel (hexan/diethyl ether 2:1). MS (FAB) : MH + 493 c) (S)-3-(1-Oxo(4-fluoro-5-N-2,2,2-trichloracetylamino-2- isopropyl)hex-3-enyl)-4-phenylmethyl-2-oxazolidinone 2 g of the compound of 301b) is dissolved in 150 ml o-xylene and stirred under reflux at 160° for 3 hours. Then o-xylene is removed and the residue is purified by column chromatography on silica- gel (toluol/ethyl acetate 98:2). MS (FAB) : MH+ 493 d) 4-Fluoro-5-N-2,2,2-trichloracetylamino-2-isopropyl-hex-3-enoic acid The title compound is prepared analogous to the procedure described by D.A. Evans et al. Org. Synth. _6 1990, but using as starting material the compound of 301c) . MS (FAB) : MH + 335 e) 5-Amino-4-fluoro-2-isopropyl-hex-3-enoic acid 899 mg of the compound of 301d) are dissolved in 20 ml ethanol and 13.5 ml 6N sodium hydroxide solution are added. This mixture is stirred for 20 hours at r.t. Then ethanol is removed and the remaining aqueous fraction is acidified with 2N HCI to pH=2 and extracted with n-butanol. The extract is evaporated and the residue is filtered through silica gel (DCM/methanol 1:1), thus yielding pure title compound. MS (FAB) : MH + 190 f) 4-Fluoro-2-isopropyl-5-tert.butoxycarbonylamino-hex-3-enoic acid 0.56 g of the compound of 301e) are dissolved in 12 ml water and 1.5 g sodium carbonate are added. To this solution 0.4 g di- tert.butylcarbonate dissolved in 12 ml tetrahydrofuran are added. This mixture is stirred at room temperature for 18 hours. Then 50 ml n-butanol and 50 ml water are added and under vigorous stir¬ ring IN HCI is added until ρH=2. The organic fraction is evapora¬ ted and the residue purified by column chromatography on silica gel (hexan/acetone 1:2) . MS (FAB) : MH + 290 [α] D = -61,3° (1% in methanol) nr ^ fr , r - PCT/EP93/01749 - 51 By repeating the above procedures but using the appropriate starting materials the following compounds may be prepared: 4-Fluoro-2-methyl-5-tert.butoxycarbonylamino-hex-3-enoic acid 4-Chloro-2-methyl-5-tert.butoxycarbonylamino-hex-3-enoic acid 4-Fluoro-2-benzyl-5-tert.butoxycarbonylamino-hex-3-enoic acid 4-Chloro-2-isoρropyl-5-tert.butoxycarbonylamino-hex-3-enoic acid 4-Methyl-2-isoproρyl-5-tert.butoxycarbonylamino-hex-3-enoic acid EXAMPLE 302: By following the procedure of Example 300 above but using the appropriate starting materials, the following compounds may be prepared: - (5-Amino-4-fluoro-2-methyl) -hex-3-enoyl-hPTH(3-36)-amide MS (Ion-Spray) : Mass 4245 - (5-Amino-4-chloro-2-methyl)-hex-3-enoyl-hPTH(3-36)-amide MS (Ion-Spray) : Mass 4260 - (5-Amino-4-fluoro-2-benzyl)-hex-3-enoyl-hPTH(3-36)-amide MS (Ion-Spray) : Mass 4320 - (5-Amino-4-chloro-2-isopropyl)-hex-3-enoyl-hPTH(3-36) -amide MS (Ion-Spray) : Mass 4289 - (5-Amino-4-methyl-2-isopropyl)-hex-3-enoyl-hPTH(3-36) -amide MS (Ion-Spray) : Mass 4269 EXAMPLE 303 : By following the procedure of Example 300 above but using the appropriate starting materials, the following compounds may be prepared: a) (5-amino-3-aza-2-isopropyl)-hexanoyl-hPTH(3-36)-amide [MS (Ion-Spray) : 4257] using as starting material: (4-aza-2-t.-butoxycarbonylamino-5-isopropyl)-hexanoic acid b) (5-amino-3-aza-3-N-acetyl-2-isopropyl) -hexanoyl-hPTH(3-36) - amide [MS (Ion-Spray) : 4299] using as starting material: (4-aza-4-N-acetyl-2-t.-butoxycarbonylamino-5-isoρropyl)-hexa- noic acid c) (5-amino-3-aza-3-N-acetyl)-hexanoyl-hPTH(3-36) -amide [MS (Ion-Spray) : 4257] using as starting material: (4-aza- 4-N-acetyl-2-t.-butoxycarbonylamino)-hexanoic acid d) (5-methylamino-3-aza-2-isopropyl)-hexanoyl-hPTH(3-36)-amide [MS (Ion-Spray) : 4271] using as starting material: [4-aza-2-(N-t.-butoxycarbonyl,N-methylamino)-5-isoρropyl]- hexanoic acid e) (5-methylamino-3-aza-3-N-methyl-2-isopropyl)-hexanoyl-hPTH(3- 36)-amide [MS (Ion-Spray): 4285] using as starting material: [4-aza-4-N-methyl-2-(N-t.-butoxycarbonylamino,N-methyl- amino) -5-isopropyl]-hexanoic acid f) (5-amino-3-aza-3-N-methyl-2-isopropyl)-hexanoyl-hPTH(3-36)- amide [MS (Ion-Spray) : 4271] using as starting material: (4-aza-4-N-methyl-2-t.-butoxycarbonylamino-5-isopropyl)- hexanoic acid g) (5-amino-3-aza-3-N-isopropyl)-hexanoyl-hPTH(3-36)-amide [MS (Ion-Spray) : 4257] using as starting material: (4-aza-4-N-isoρropyl-2-t.-butoxycarbonylamino-5-isopropyl)- hexanoic acid h) [1-cyclopentane-l-amino-l-carboxylic acid(psi CH 2 -NH) -Val 2 ]- hPTH(1-36)-amide using l-cyclopentane-1-t.-butoxycarbonyl- amino-1-carboxylic acid (psi CH2-NH) -Val-OH as starting material. EXAMPLE 304: By following the procedure of Example 3a) above but using the appropriate starting material, the following compound may be prepared: (5-amino-3-aza-2-isopropyl)-hexanoyl-[Leu 8 ,Ala 1 -,Gin 18 ,Ala 1 - ]hPTH (3-36)OH [MS (Ion-Spray): 4135] using as starting material: (4-aza-2-t.-butoxycarbonylamino)-hexanoic acid EXAMPLE 305: (4-Aza-4-N-acetyl-2-tert.butoxycarbonylamino-5- isopropyl)-hexanoic acid a) Methyl (4-aza-2-tert.butoxycarbonylamino-5-isopropyl)-hexanoic acid Boc-Ala-Val-OMe is treated with the Lawesson-reagent (S.-O. La- wesson, et al. Tetrahedron 1981, 37, 3635) . The resulting endothiopeptide is then reduced in accordance with the procedure described by F.S. Guziec et. al. THL, 1990, 23-26. MS (El) : MH + 289 b) Methyl (4-aza-4-N-acetyl-2-tert.butoxycarbonylamino-5- isopropyl) hexanoate 264 mg of the compound of 305a) is dissolved in 5 ml DCM and then 0.14 ml triethylamin and 0.072 ml acetyl chloride are added. This mixture is stirred for 24 hours at 40°. After addition of 50 ml DCM, the solution is washed twice with water. The organic frac¬ tion is dried and evaporated. The title compound thus obtained is purified by column chromatography (hexan/ethyl acetate 4:1) MS (El) : M + 330 c) (4-Aza-4-N-acetyl-2-tert.butoxycarbonylamino-5- isopropyl) -hexanoic acid 356 mg of the compound of 305b) are dissolved in 4 ml methanol/- water 3:1 and 53 mg lithium hydroxide are added. This mixture is stirred at 60° for two hours. Then 25 ml DCM are added and IN HCI is added under vigorous stirring until pH=2. The organic fraction is separated, dried and evaporated, thus yielding the title compound in pure form. MS (FAB) : MH + 317 By repeating the procedure but using the appropriate starting materials, following compounds may be obtained: (4-Aza-4-N-acetyl-2-tert.butoxycarbonylamino)-hexanoic acid (4-Aza-2-tert.butoxycarbonylamino-5-isoproρyl)-hexanoic acid [4-aza-2-(N-t.-butoxycarbonyl,N-methylamino)-5-isopropyl]- hexanoic acid (4-aza-4-N-methyl-2-t.-butoxycarbonylamino-5-isopropyl)-hexanoic acid (4-aza-4-N-isopropyl-2-t.-butoxycarbonylamino-5-isopropyl)- hexanoic acid (4-aza-2-t.-butoxycarbonylamino)-hexanoic acid The compounds of Examples 1 to 300 and 302 to 304 show correct amino acid ratios in quantitative amino acid analysis. In the following examples illustrating the recombinant process of the invention, if not otherwise specified, the standard procedures described in Ausubel et al; 1991; Current Protocols in Molecular Biology, John Wiley & Sons, New York are used. EXAMPLE 306: Cloning bacteriophage T4 gene 55 Two DNA fragments, one containing the entire coding sequence of bacteriophage T4 gene 55, and the other fragment encoding part of it are amplified by polymerase chain reaction (PCR) using purified T4 DNA as the template. Oligonucleotides which contain Ndel or BamHI endonuclease recognition sequences are used as primers. The PCR reactions (25 cycles, each 30" 94 °C, 30" 50 °C, 30" 72 °C) are performed with 1 ng of template and 100 pM of the upstream primer (SEQ ID No. 5, the Ndel recognition site being provided by nucleotides 7-12 thereof) and 100 pM of the downstream primer (SEQ ID No. 6, the BamHI recognition site being provided by nucleotides 5-10 thereof) in 100 μl reaction buffer containing 10 mM Tris-HCl, 50 mM KC1, 1.5 mM MgCl 2 , 0.2 mM of each of dATP, dCTP, dGTP, dTTP, and 0.1% Triton X 100, pH 9.0. A 0.6kb fragment is obtained. The truncated form of gene 55 is prepared by PCR as described for the entire gene, except that a different oligonucleotide is used as downstream primer (SEQ ID No. 7, the BamHI recognition site being provided by nucleotides 5-10 thereof). A 0.35 kb fragment is obtained. The 0.6 kb and 0.35 kb DNA fragments are digested with restriction endonucleases Ndel/BamHI and are cloned into a Ndel/BamHI digest of expression vector pET17B (obtained from Novagen) . The 0.6 kb DNA fragment encodes the entire gp55 protein (188 amino acid residues - see SEQ ID No.l), whereas the 0.35 kb fragment encodes a 12 kD amino-terminal fragment of gp55 (112 amino acid residues - see SEQ ID No. 3) . EXAMPLE 307: Preparation and cloning of the DNA encoding hPTH (l-38)OH DNA fragments encoding a) the linker peptide corresponding to amino acid residues 110-115 of SEQ ID No. 1 and hPTH (1-38) or b) the linker peptide corresponding to amino acid residues 186-191 of SEQ ID No.3 and hPTH (1-38) are generated by PCR using a cloned synthetic PTH (1-38) coding sequence as a template. The oligonucleotides encoding the linker a) (SEQ ID No. 8), or encoding linker b(SEQ ID No.9), are used as upstream primers. The downstream primer is shown as SEQ ID No. 10. The upstream primers each incorporate a BamHI cloning site and the downstream primer contains a Xhol recognition site (nucleotides 5-10 of each sequence) . The PCR reaction is performed under the same conditions as described in Example 306. After cleavage with BamHI and Xhol, the 0.23 kb PCR products are inserted into BamHI-XhoI digests of the gp55-pET17B plasmids, obtained in Example 306. For expression of the fusion proteins the resultant plasmid constructs are transformed into E.coli BL21 (DE3) LysE and single bacterial colonies are further propagated. The expression of the fusion proteins is obtained by incubating a preculture at 37°C on a rotary shaker overnight in circle growth medium (Bio 101) . A main culture is inoculated with the preculture making up 1 to 5 % of the volume of the main culture. The main culture is then fermented at a temperature of 37°C and at a pH of 6.9 to 7.1 whilst being aerated at 10 1/min and agitated at 200-400 rpm. Expression is induced by the addition of 1 mM IPTG as soon as the culture reaches an 0D 550 of about 1.0 to 5.0. After induction the fermentation is continued for five hours and then the fermentation broth is harvested without killing the E. coli cells. The harvested cells are spun down with a tubular centrifuge and resuspended in sample buffer and assayed for expression by SDS PAGE. The cell pellet is then frozen until purification. The procedures and host cells used are fully described in Studier et al; 1990; "Use of T7 RNA Polymerase to direct expression of Cloned Genes", Methods in Enzymology, Academic Press, pages 60 to 89. EXAMPLE 308: Preparation of inclusion bodies Frozen E. coli pellets obtained from Example 307 are resuspended to 25% w/v in Buffer A (50mM Tris pH 8.0; containing 2mM DTT, 5mM Benzamidine-HCl, 1.5mM MgCl 2 , l.OmM MnCl 2 , lOμg/ml DNAse 1 and 2mg/ml Lysozyme) and mixed by stirring for 1 hour at room temperature. The resuspended cells are lysed by passage through a Manton-Gaulin homogeniser (2 passes at 1200 bar) and the resultant lysate kept on ice. The lysate is diluted 2 fold with ice-cold buffer B (50mM Tris pH 8.0; containing 2mM DTT, 5mM Benzamidine-HCl and 4mM EDTA) and centrifuged for 30min at 27,500g. The supernatant from the centrifuge is carefully removed and discarded. The pellet is resuspended in buffer B to 25% w/v, passed once more through the Manton-Gaulin and centrifuged as before. This process is repeated once using buffer B and once using water. The resultant inclusion body pellets are weighed and frozen at -20°C until required. EXAMPLE 309: Solubilisation and cleavage of gp55-Asp-Pro-Pro-(l- 38)hPTH-0H inclusion bodies Frozen inclusion bodies containing gp55-Asp-Pro-Pro-(l-38)hPTH as obtained in Example 308 are suspended in 10 mM HCI acid solution (analytical grade) to a final concentration of 6%w/v. The solution is incubated for 24 hours at 50°C and the reaction terminated by addition " 1 volume of aqueous 100 mM NaOAc solution. The diluted .-.. -ernatant is clarified by centrifugation at 27,500g for 30 minutes and filtered through a glass fibre filter. EXAMPLE 310: Solubilisation and cleavage of gp55-Asn-Gly-Pro-(l- 38)hPTH inclusion bodies Frozen inclusion bodies containing gp55-Asn-Gly-Pro-(1-38)PTH and obtained from example 308 are dissolved in 6M Guanidine-HCl (containing 2M Hydroxylamine-HCl and brought to pH 9.0 by addition of 4.5M LiOH) to give an estimated 5mg/ml protein. The pH is readjusted to pH 9 by further addition of LiOH and the solution incubated for 4 hours at 45°C. The reaction is terminated by addition of formic acid to pH 4 and the solution centrifuged and filtered as described in example 309. EXAMPLE 311: Preparative HPLC of Gly-Pro and Pro-Pro (1-38)hPTH Filtered cleavage supernatants are analysed on analytical reversed phase HPLC (Orpogen HD-Gel-RP-7s-300; 4 x 150mm column) and compared with a known (1-38)PTH standard (Bachem) to determine the PTH concentration. The column is equilibrated with 85% HPLC buffer A (90% water, 10% acetonitrile; containing 0.1%v/v TFA) and 15% HPLC buffer B (10% water, 90% acetonitrile; containing 0.1% TFA) and is eluted with a gradient of 15% HPLC buffer B to 100% HPLC buffer B over 15 minutes at a flow rate of 0.75ml/min. Depending upon the scale of the preparation, supernatants are either loaded on a 1.0 x 25cm C4 Vydac or a 2.2 x 25cm C4 Vydac. The columns are equilibrated with 85% HPLC buffer A and 15% HPLC buffer B at flow rates of 4ml/min and lOml/min respectively. The columns are eluted with gradients of 15%B to 85%B over 80ml and 15%B to 55%B over 300ml respectively. Gly-Pro-hPTH(l-38) or Pro-Pro-hPTH(l-38) peaks are collected manually and the acetonitrile is later removed under vacuum. Analytical HPLC is used to determine the peptide concentration both after cleavage and in the collected fractions. The solvent free peptide solutions are diluted with an equal volume of lOOmM sodium acetate and the pH adjusted, if necessary, to pH 5.4. Following filtration (0.2um), the solution is loaded on a cation exchange column (either Mono S or SP-Sepharose High Performance, packed into HRlO/10 or XK16/10 columns respectively) equilibrated with 50mM sodium acetate pH 5.4 (buffer C) . The column is eluted with a 0 to 500mM NaCl gradient in buffer C over 7.5 column volumes. 10ml fractions are collected and the X-X-(l-38)hPTH peak is pooled. The peptide concentration is determined as before using HPLC. This column serves both to exchange the peptides into a more physiological buffer and to remove additional peptides produced by chemical cleavage of the fusion protein itself. EXAMPLE 312: Enzymatic removal of X-X from X-X-(l-38)hPTH-OH Pooled peptide fractions, as obtained in Example 311, (concentration range 1.5 - 2.0 mg/ml) are brought to pH 8.0 by addition of solid Tris. Purified X-Prolyl dipeptidase (0.5mg/ml in PBS pH 7.2) (Nardi et al. (1991) App. Env. Microbiol. 57, No.l, 45-50) is added to 1:1000 and the solution is incubated for 24h at 37 C. The reaction is stopped by addition of TFA to 0.2% (pH = 5.0) and the resultant (1-38)PTH is isolated using preparative HPLC (using the same conditions as described in Example 6) . The solvent is removed and the product is lyophilised after removal of aliquots for N-terminal sequence and mass spectroscopic analyses. Examples of the yields which are obtained using the two fusion protein approaches described above are as follows: Gen55-Asp-Pro-Pro-hPTH(l-38)OH (using the "truncated" form of Gen55) Under partially optimized fermentation conditions, a 215 g wet cell pellet is obtained from a 10 litre fermentation. The percentage level of expression of the fusion protein is approximately 37%. From this pellet, 31 g of inclusion bodies are isolated. The protein purity (with respect to the fusion protein) of these bodies is 61%. After solubilisation, cleavage and centrifugation/filtration approximately 620mg Pro-Pro-PTH are detected. This material yields 580mg Pro-Pro-PTH after subsequent C4-Vydac HPLC. After dilution, cation-exchange on Mono S, digestion with X-Prolydipeptidypeptidase (at a Pro-Pro-PTH concentration of 2mg/ml) , HPLC and lyophilisation, 440mg of lyophilized pure product with full biological activity is obtained. This represents a yield of 71% between the stopped cleavage step and the final product. Gen55-Asn-Gly-Pro-hPTH(l-38)OH (using the "long" form of Gen55) From a non-optimized 20 litre fermentation a 78g wet cell pellet with 50% expression of the fusion protein is harvested. Following lysis and centrifugation, 18g of "90% pure" inclusion bodies are obtained. Following the acid stop step and centrifugation/fil¬ tration about 470mg Gly-Pro-PTH are detected. After HPLC on C4-Vydac, 355mg of peptide are detected, decreasing to 321mg after SP-Sepharose cation-exchange. Enzymatic removal of the Gly and Pro residues is carried out at 2mg/ml. After the final HPLC step and lyophilization, 244mg of pure, fully biologically active hPTH(l-38)OH is recovered representing a yield of 52% from the stopped cleavage reaction stage. Compounds of Examples 25, 26, 56 and 86 to 164 are also prepared using the process of Examples 306 to 312. The compounds of the invention in free form or in the form of pharmaceutically acceptable salts and complexes exhibit valuable pharmacological properties as indicated in animal tests and are therefore indicated for therapy. The biological activity of the compounds of the invention is assessed in vitro by measuring their ability of stimulating the synthesis of cyclic AMP in UMR 106-06 rat and SaOS-2 human osteosarcoma cells according to the method of Marcus and Aurbach in Endocrinology, _85, 801-810 (1969) . Rat osteosarcoma UMR 106 cells are grown to confluence in Eagle's Minimum Essential Medium - 10% FCS in 12 well plates, human SaOS-2 osteosarcoma cells are grown in McCoy's 5A medium - 10% FCS. The medium is then changed to medium with 2% FCS and 1-5 μCi/well [3H]-adenine is added. Two hours later, cells are washed twice with serum-free medium and incubated in DMEM - 1% BSA containing 1 mM 3-isobutyl-l-methyl- xanthine to exclude actions on phosphodiesterases. Test substances are added 20 min later. The reaction is stopped and cAMP extracted after 15 min by adding ice cold 5% trichloroacetic acid. A carrier solution (0.5 ml/well) containing 5 mM of unlabelled adenine, adenosine, AMP, ADP, ATP, and cAMP as well as 0.4 μCi [14C]-adenosine for determination of recovery is added. [3H]-cAMP is separated using serial Dowex 50W-X4 (200-400 mesh) and alumina chromatography and counted. Results are calculated in % of solvent control and EC 50 values determined from DRC curves. Compounds of the invention stimulate cAMP production in UMR 106-06- rat and SaOS-2 human osteosarcoma cells at a concentration of 10" 11 to 10" 6 M. The compounds of the invention also have binding affinity to PTH receptors, e.g. as follows: Chicken [Tyr 36 ]PTHrP (1-36)amide is iodinated to a specific activity of 2,200 Ci/mmol using the lactoperoxidase method (Anawa Lab. AG, Wangen) . Monolayers of opossum kidney cells are washed with 200 μl DMEM and HAM's F12 (1:1) containing 1% BSA and incubated at 16°C with 50.000cpm of [ 125 I-Tyr 36 ]chPTHrP (1-36)- amide per well in the presence or absence of 1 μM [Tyr 36 ]chPTHrP- (1-36)amide. After incubation, cells are washed with 0.5 ml medium (4°C), lysed with 0.5 ml IN NaOH and radioactivity is determined. Specific binding is defined as total binding minus nonspecific binding. Competition curves are analyzed using SCTFIT, a non-linear regression computer program (Feyen et al, 1992, Biochem. Biophys. Res. Commun. 187:8-13) and data presented as mean pK D values (n=2 to 3) . Compounds of the invention show in this test a binding affinity expressed as a mean pK D value of from 7 to 10. Furthermore, the compounds of the invention increase plasma calcium level after continuous s.c. infusion, e.g. as determined in male thyroparathyroidectomized Wistar rats weighing 140 to 170 g. 5 days after thyroparathyroidectomy, rats are implanted in the neck with Alzet minipumps and test compounds infused at rates of 0.3 to 30 μg/day/rat. Blood is drawn by retro-orbital puncture in the morning of days 1, 2, 3, and 6 thereafter and plasma calcium concentrations are determined photometrically. In this test com¬ pounds of the invention increase plasma calcium. The compounds of the invention are accordingly indicated for pre¬ venting or treating all bone conditions which are associated with increased calcium depletion or resorption or in which calcium fixation in the bone is desirable, e.g. osteoporosis of various genesis (e.g. juvenile, menopausal, post-menopausal, post-trauma- tic, caused by old age or by cortico-steroid therapy or inactivi¬ ty) , fractures, osteopathy, including acute and chronic states associated with skeletal demineralisation, osteo-malacia, perio- dontal bone loss or bone loss due to arthritis or osteoarthritis or for treating hypoparathyroidism. The compounds of the invention are particularly indicated for preventing or treating osteoporosis of various genesis. For all the above uses, an indicated daily dosage is in the range from about 0.003 to about 10 mg preferably 0.003 to 3, more preferably 0.01 to 1 mg of a compound of the invention. Compounds of the invention may be administered once a day or up to twice a week. The compounds of the invention may be administered in free form or in pharmaceutically acceptable salt form or complexes. Such salts and complexes may be prepared in conventional manner and exhibit the same order of activity as the free compounds. The present invention also provides a pharmaceutical composition comprising a compound of the invention in free base form or in pharmaceutically acceptable salt form or complex form in associa¬ tion with a pharmaceutically acceptable diluent or carrier. Such compositions may be formulated in conventional manner. The com¬ pounds of the invention may be administered by any conventional route, for example parenterally e.g. in form of injectable solu¬ tions or suspensions, enterally, e.g. orally, for example in the form of tablets or capsules or in a transdermal, nasal or a sup¬ pository form. In accordance with the foregoing the present invention further provides: a) a compound of the invention or a pharmaceutically acceptable salt or complex thereof for use as a pharmaceutical; b) a method for improving bone formation, e.g. preventing or treating all bone conditions which are associated with in¬ creased calcium depletion or resorption or in which calcium fixation in the bone is desirable, e.g. osteoporosis of va¬ rious genesis (e.g. juvenile, menopausal, post-menopausal, post-traumatic, caused by old age or by cortico-steroid the¬ rapy or inactivity), fractures, osteopathy, including acute and chronic states associated with skeletal demineralisation, osteo-malacia, periodontal bone loss or bone loss due to arthritis or osteoarthritis, or for treating hypoparathyro- idiom in a subject in need of such treatment, which method comprises administering to said subject an effective amount of a compound of the invention or a pharmaceutically acceptable salt or complex thereof; c) a compound of the invention or a pharmaceutically acceptable salt or complex thereof for use in the preparation of a phar¬ maceutical composition for use in the method as in b) above. According to a further embodiment of the invention, the compounds of the invention may be employed as adjunct or adjuvant to other therapy, e.g. a therapy using a bone resorption inhibitor, for example as in osteoporosis therapy, in particular a therapy em¬ ploying calcium, a calcitonin or an analogue or derivative thereof, e.g. salmon, eel or human calcitonin, a steroid hormone, e.g. an estrogen, a partial estrogen agonist or estrogen-gestagen combination, a biphosphonate, vitamin D or an analog thereof, or any combination thereof. When the compounds of the invention are administered in conjunc¬ tion with, e.g. as an adjuvant to bone resorption inhibition the- rapy, dosages for the co-administered inhibitor will of course vary depending on the type of inhibitor drug employed, e.g. whe¬ ther it is a steroid or a calcitonin, on the condition to be treated, whether it is a curative or preventive therapy, on the regimen and so forth. In accordance with the foregoing the present invention provides in a yet further aspect: d) a method for improving bone formation, e.g. preventing or treating calcium depletion, for example for preventing or treating any of the specific conditions or diseases herein¬ before set forth, in a subject in need of such a treatment which method comprises administering to said subject an ef¬ fective amount of a) a compound of the invention and b) a second drug substance, said second drug substance being a bone resorption inhibitor, for example as indicated above. Compounds of Examples 20, 29, 37, 49 and 50 are preferred. SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: (A) NAME: SANDOZ LTD (B) STREET: PO BOX (C) CITY: BASEL (D) STATE: BS (E) COUNTRY: SWITZERLAND (F) POSTAL CODE (ZIP) : CH 4002 (G) TELEPHONE: 061 324 1111 (H) TELEFAX: 061 322 7572 (I) TELEX: 965 050 55 (ii) TITLE OF INVENTION: Organic Compounds (iii) NUMBER OF SEQUENCES: 12 (iv) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentln Release #1.0, Version #1.25 (EPO) (2) INFORMATION FOR SEQ ID NO:1: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 717 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (vi) ORIGINAL SOURCE: (A) ORGANISM: Bateriophage T4/Homo sapiens (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 101..559 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: AGATCTCGAT CCCGCGAAAT TAATACGACT CACTATAGGG AGACCACAAC GGTTTCCCTC 60 TAGAAATAAT TTTGTTTAAC TTTAAGAAGG AGATATACAT ATG TCA GAA ACT AAG 115 Met Ser Glu Thr Lys 1 5 CCT AAA TAT AAT TAC GTA AAC AAT AAA GAG CTT TTA CAA GCT ATT ATT 163 Pro Lys Tyr Asn Tyr Val Asn Asn Lys Glu Leu Leu Gin Ala lie He 10 15 20 GAT TGG AAA ACA GAA TTA GCA AAT AAT AAA GAC CCA AAT AAA GTA GTT 211 Asp Trp Lys Thr Glu Leu Ala Asn Asn Lys Asp Pro Asn Lys Val Val 25 30 35 CGT CAG AAT GAT ACT ATC GGA TTA GCC ATT ATG CTT ATT GCA GAA GGC 259 Arg Gin Asn Asp Thr lie Gly Leu Ala lie Met Leu lie Ala Glu Gly 40 45 50 TTA TCT AAA CGT TTC AAC TTT TCA GGA TAC ACC CAG TCT TGG AAA CAA 307 Leu Ser Lys Arg Phe Asn Phe Ser Gly Tyr Thr Gin Ser Trp Lys Gin 55 60 65 GAA ATG ATT GCA GAT GGT ATA GAA GCT TCT ATT AAG GGG CTT CAC AAT 355 Glu Met lie Ala Asp Gly lie Glu Ala Ser lie Lys Gly Leu His Asn 70 75 80 85 TTT GAT GAA ACG AAA TAT AAA AAC CCA CAT GCG TAT ATA ACT CAA GCT 403 Phe Asp Glu Thr Lys Tyr Lys Asn Pro His Ala Tyr lie Thr Gin Ala 90 95 100 TGT TTT AAT GCA TTC GTC CAA CGT GGA TCC ATC GAT CCA CCA TCC GTA 451 Cys Phe Asn Ala Phe Val Gin Arg Gly Ser lie Asp Pro Pro Ser Val 105 110 115 TCA GAA ATA CAA CTA ATG CAT AAT CTG GGT AAA CAT CTG AAT TCA ATG 499 Ser Glu lie Gin Leu Met His Asn Leu Gly Lys His Leu Asn Ser Met 120 125 130 GAA CGT GTA GAA TGG CTG CGT AAA AAA CTG CAG GAT GTA CAT AAT TTT 547 Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin ASD Val His Asn Phe 135 140 145 GTA GCT CTG GGT TAACTCGAGC AGATCCGGCT GCTAACAAAG CCCGAAAGGA 599 Val Ala Leu Gly 150 AGCTGAGTTG GCTGCTGCCA CCGCTGAGCA ATAACTAGCA TAACCCCTTG GGGCCCTTGG 659 GGCCTCTAAA CGGGTCTTGA GGGGTTTTTT GCTGAAAGGA GGAACTATAT CCGGATAA 717 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 153 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: Met Ser Glu Thr Lys Pro Lys Tyr Asn Tyr Val Asn Asn Lys Glu Leu 1 5 10 15 Leu Gin Ala lie lie Asp Trp Lys Thr Glu Leu Ala Asn Asn Lys Asp 20 25 30 Pro Asn Lys Val Val Arg Gin Asn Asp Thr lie Gly Leu Ala lie Met 35 40 45 Leu lie Ala Glu Gly Leu Ser Lys Arg Phe Asn Phe Ser Gly Tyr Thr 50 55 60 Gin Ser Trp Lys Gin Glu Met lie Ala Asp Gly lie Glu Ala Ser lie 65 70 75 80 Lys Gly Leu His Asn Phe Asp Glu Thr Lys Tyr Lys Asn Pro His Ala 85 90 95 Tyr lie Thr Gin Ala Cys Phe Asn Ala Phe Val Gin Arg Gly Ser lie 100 105 110 Asp Pro Pro Ser Val Ser Glu lie Gin Leu Met His Asn Leu Gly Lys 115 120 125 His Leu Asn Ser Met Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin 130 135 140 Asp Val His Asn Phe Val Ala Leu Gly 145 150 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 945 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (vi) ORIGINAL SOURCE: (A) ORGANISM: Bacteriophage T4/Homo sapiens (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 101..787 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: AGATCTCGAT CCCGCGAAAT TAATACGACT CACTATAGGG AGACCACAAC GGTTTCCCTC 60 TAGAAATAAT TTTGTTTAAC TTTAAGAAGG AGATATACAT ATG TCA GAA ACT AAG 115 Met Ser Glu Thr Lys 1 5 CCT AAA TAT AAT TAC GTA AAC AAT AAA GAG CTT TTA CAA GCT ATT ATT 163 Pro Lys Tyr Asn Tyr Val Asn Asn Lys Glu Leu Leu Gin Ala lie lie 10 15 20 GAT TGG AAA ACA GAA TTA GCA AAT AAT AAA GAC CCA AAT AAA GTA GTT 211 Asp Trp Lys Thr Glu Leu Ala Asn Asn Lys Asp Pro Asn Lys Val Val 25 30 35 CGT CAG AAT GAT ACT ATC GGA TTA GCC ATT ATG CTT ATT GCA GAA GGC 259 Arg Gin Asn Asp Thr lie Gly Leu Ala lie Met Leu lie Ala Glu Gly 40 45 50 TTA TCT AAA CGT TTC AAC TTT TCA GGA TAC ACC CAG TCT TGG AAA CAA 307 Leu Ser Lys Arg Phe Asn Phe Ser Gly Tyr Thr Gin Ser Trp Lys Gin 55 60 65 GAA ATG ATT GCA GAT GGT ATA GAA GCT TCT ATT AAG GGG CTT CAC AAT 355 Glu Met lie Ala Asp Gly lie Glu Ala Ser lie Lys Gly Leu His Asn 70 75 80 85 TTT GAT GAA ACG AAA TAT AAA AAC CCA CAT GCG TAT ATA ACT CAA GCT 403 Phe Aso Glu Thr Lys Tyr Lys Asn Pro His Ala Tyr lie Thr Gin Ala 90 95 100 TGT TTT AAT GCA TTC GTC CAA CGT ATT AAA AAA GAA CGT AAG GAA GTT 451 Cys Phe Asn Ala Phe Val Gin Arg lie Lys Lys Glu Arg Lys Glu Val 105 110 115 GCA AAG AAA TAT AGT TAC TTC GTT CAC AAT GTC TAT GAC AGC CGT GAC 499 Ala Lys Lys Tyr Ser Tyr Phe Val His Asn Val Tyr Asp Ser Arg Asp 120 125 130 GAC GAT ATG GTT GCG TTA GTA GAT GAA ACT TTT ATT CAA GAC ATC TAT 547 ASD Asp Met Val Ala Leu Val Asp Glu Thr Phe He Gin Asp lie Tyr 135 140 145 GAT AAA ATG ACG CAT TAC GAA GAA TCA ACC TAT AGA ACA CCG GGG GCT 595 Asp Lys Met Thr His Tyr Glu Glu Ser Thr Tyr Arg Thr Pro Gly Ala 150 155 160 165 GAA AAG AAA AGT GTT GTA GAT GAT TCT CCT AGT TTG GAT TTT TTA TAT 643 Glu Lys Lys Ser Val Val Asp Asp Ser Pro Ser Leu Asp Phe Leu Tyr 170 175 180 GAG GCT AAC GAT GGA TCC GTT AAC GGT CCA TCC GTA TCA GAA ATA CAA 691 Glu Ala Asn Asp Gly Ser Val Asn Gly Pro Ser Val Ser Glu lie Gin 185 190 195 CTA ATG CAT AAT CTG GGT AAA CAT CTG AAT TCA ATG GAA CGT GTA GAA 739 Leu Met His Asn Leu Gly Lys His Leu Asn Ser Met Glu Arg Val Glu 200 205 210 TGG CTG CGT AAA AAA CTG CAG GAT GTA CAT AAT TTT GTA GCT CTG GGT 787 Trp Leu Arg Lys Lys Leu Gin Asp Val His Asn Phe Val Ala Leu Gly 215 220 225 TAACTCGAGC AGATCCGGCT GCTAACAAAG CCCGAAAGGA AGCTGAGTTG GCTGCTGCCA 847 CCGCTGAGCA ATAACTAGCA TAACCCCTTG GGGCCCTTGG GGCCTCTAAA CGGGTCTTGA 907 GGGGTTTTTT GCTGAAAGGA GGAACTATAT CCGGATAA _ 945 (2) INFORMATION FOR SEQ ID NO:4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 229 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4: Met Ser Glu Thr Lys Pro Lys Tyr Asn Tyr Val Asn Asn Lys Glu Leu 1 5 10 15 Leu Gin Ala lie lie Asp Trp Lys Thr Glu Leu Ala Asn Asn Lys Asp 20 25 30 Pro Asn Lys Val Val Arg Gin Asn Asp Thr He Gly Leu Ala lie Met 35 40 45 Leu lie Ala Glu Gly Leu Ser Lys Arg Phe Asn Phe Ser Gly Tyr Thr 50 55 60 Gin Ser Trp Lys Gin Glu Met lie Ala Asp Gly lie Glu Ala Ser lie 65 70 75 80 Lys Gly Leu His Asn Phe Asp Glu Thr Lys Tyr Lys Asn Pro His Ala 85 90 95 Tyr lie Thr Gin Ala Cys Phe Asn Ala Phe Val Gin Arg lie Lys Lys 100 105 110 Glu Arg Lys Glu Val Ala Lys Lys Tyr Ser Tyr Phe Val His Asn Val 115 120 125 Tyr Asp Ser Arg Asp Asp Asp Met Val Ala Leu Val Asp Glu Thr Phe 130 135 140 lie Gin Asp lie Tyr Asp Lys Met Thr His Tyr Glu Glu Ser Thr Tyr 145 150 155 160 Arg Thr Pro Gly Ala Glu Lys Lys Ser Val Val Asp Asp Ser Pro Ser 165 170 175 Leu Asp Phe Leu Tyr Glu Ala Asn Asp Gly Ser Val Asn Gly Pro Ser 180 185 190 Val Ser Glu He Gin Leu Met His Asn Leu Gly Lys His Leu Asn Ser 195 200 205 Met Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin Asp Val His Asn 210 215 220 Phe Val Ala Leu Gly 225 (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 27 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5 : GAGGTGCAT TGTCAGAAAC TAAGCCT 27 (2) INFORMATION FOR SEQ ID NO: 6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 40 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 6: GGTCGGATCC ATCGTTAGCG TTAGCCTCAT ATAAAAAATC 40 (2) INFORMATION FOR SEQ ID NO:7: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 28 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7 : GGTCGGATCC TACGTTGGAC GAATGCAT 28 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 42 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8: GAGTGGATCC ATCGATCCAC CATCCGTATC AGAAATACAA CT 42 (2) INFORMATION FOR SEQ ID NO: 9: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 42 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 9: GAGTGGATCC GTTAACGGTC CATCCGTATC AGAAATACAA CT 42 (2) INFORMATION FOR SEQ ID NO:10: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 34 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (v) FRAGMENT TYPE: internal (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10: TCTACTCGAG TTAACCCAGA GCTACAAAAT TATG 34 (2) INFORMATION FOR SEQ ID NO: 11: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 34 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: unknown (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Homo sapiens (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11: Ser Val Ser Glu lie Gin Leu Met His Asn Leu Gly Lys His Leu Asn 1 5 10 15 Ser Met Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin Asp Val His 20 25 30 Asn Phe (2) INFORMATION FOR SEQ ID NO:12: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 36 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: unknown (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Homo sapiens (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12: Ser Val Ser Glu He Gin Leu Met His Asn Leu Gly Lys His Leu Asn 1 5 10 15 Ser Met Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin Asp Val His 20 25 30 Asn Phe Val Ala 35 (2) INFORMATION FOR SEQ ID NO:13: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 38 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: unknown (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: NO (iii) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Homo sapiens (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13: Ser Val Ser Glu lie Gin Leu Met His Asn Leu Gly Lys His Leu Asn 1 5 10 15 Ser Met Glu Arg Val Glu Trp Leu Arg Lys Lys Leu Gin Asp Val His 20 25 30 Asn Phe Val Ala Leu Gly 35

Claims: CLAIMS A PTH compound having PTH-like activity and comprising at least one modification, said modification being either 1. at least one radical selected from a L- or D-α-amino acid, C 2 - 6 alcoxycarbonyl and optionally substituted C x _ 8 alkyl, C 2 - 8 alkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-C 1 _ 4 alkyl and attached to the terminal amino group of the PTH compound, and/or at least one radical selected from C 2 - 6 alcoxycarbonyl and optionally substituted Cx-salkyl, C2_salkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl and attached to one or more side chain amino groups of the PTH compound, or 2. at least one α-amino acid unit in the positions 1 to 38 of a naturally occurring PTH seguence being replaced by a natural or unnatural amino acid unit optionally in protected form, whereby the α-amino acid units present in positions 1 and 2 at the amino terminus of the PTH sequence together may be replaced by a pseudo-peptide, or a combination of such modifications, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 lcoxycarbonyl or optionally substituted Cι_salkyl, C 2 -s lkenyl, C 2 -s lkynyl, aralkyl, C 2 - 8 alkynyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 1 is Gly, D-Ser, D-Ala or Tyr; or ii. the α-amino acid in position 2 is Ala, D-Val, Lys, Arg or Cit and the α-amino acid in position 34 is Tyr; or the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr and optionally the α-amino acids in positions 8 and 18 are each Nle; or iii. the α-amino acid in positions 3 and/or 6 and/or 9 are replaced by a natural or unnatural amino acid; or iv. the α-amino acid in position 23 is replaced by Ala, Arg, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Lys, Met, Pro, Ser or Thr; or v. the α-amino acid in position 25 and/or 26 and/or 27 is replaced by Ala, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr or Val; or vi. the α-amino acids in positions 8 and 18 are each Nle or each Met (0) and optionally the α-amino acid in position 34 is Tyr; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 34 is Tyr and either the α-amino acid in position 12 is L- or D-Pro, L- or D-Ala, Aib or NMeGly or the α-amino acid in position 23 is Phe, Leu, Nle, Val, Tyr, α-Nal or β-Nal; or vii. the α-amino acid in position 28 is Lys and the α-amino acid in position 30 is Leu; or viii.the α-amino acid in position 1 is Aib; and/or the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp; and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr; and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl) , D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys (Fmoc) , D-Phe or D-Asn; and/or the α-amino acid in position 13 is Leu; and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His; and/or the α-amino acid in position 23 is 2-(l,3-dithiolane- 2-yl)Trp; and/or the α-amino acid in position 25 and/or in position 26 is His; and/or the α-amino acid in position 27 is Gin or Leu; or ix. the α-amino acid in position 8 and/or 18 is Ala or Ser; or the α-amino acid in position 8 and/or 18 is Ala, Val, Leu, He, Ser or Trp and the α-amino acid in position 34 is Tyr; or the PTH compound is other than PTH(1-84) wherein i. the α-amino acid in position 1 is Tyr, Val, Pro, Asp or Cys; or ii. the α-amino acid in position 2 is Ala, Glu, Leu, Ser or Arg; or iii. the α-amino acid in positions 3 and/or 6 and/or 9 are replaced by a natural or unnatural amino acid; or iv. the α-amino acid in position 23 is replaced by Ala, Arg, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Lys, Met, Pro, Ser or Thr; or v. the α-amino acid in position 25 and/or 26 and/or 27 is replaced by Ala, Asn, Asp, Cys, Gin, Glu, Gly, His, He, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr or Val; or . vi. the α-amino acid in position 8 is Met, Met(O), Ala, Val, Leu, He, Ser, Trp, Asn, Gin, Asp, Glu, Lys, Arg, Tyr or Gly and the α-amino acid in position 18 is Leu; or the α-amino acid in position 8 and/or 18 is Ala, Val, Leu, He, Ser or Trp, and optionally the α-amino acid in position 34 is Tyr; or the α-amino acid in position 8 and in position 18 are each Met(0); or the α-amino acid in position 8 is Leu and the α-amino acid in position 18 is Met(0); or vii. the α-amino acid in position 26 is Gin; the compound is other than Pro°PTH(l-84) or [Met 0 ,Leu 8 , Leu 18 ]PTH(l-84); or the PTH compound is other than hPTH(l-36) wherein the α-amino acid in position 36 is Leu; in free form or in salt form or complex form. 2. A PTH compound according to claim 1 comprising at least one amino acid unit replaced in one of the following positions of the PTH sequence: 1, 2, 3, 8-11, 13 to 19, 21, 22, 29 to 34. 3. A PTH compound according to claim 1 or 2 wherein the α-amino acid units in positions 1 and 2 at the amino terminus of the PTH sequence is replaced by a pseudo-dipeptide. 4. A PTH compound according to claim 1 or 2, wherein the α-amino acid unit in position 1 and/or the α-amino acid unit in position 2 of the N-terminus of the PTH sequence is replaced by an optionally protected natural or unnatural amino acid residue, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 alkoxycarbonyl or optionally substituted Ci-salkyl, C 2 -βalkenyl, C2-s lkynyl, aralkyl, aralkenyl or C 3 _ 6 Cycloalkyl-Cι_ alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 1 is Aib, Gly, D-Ser, D-Ala or Tyr; or ii. the α-amino acid in position 2 is Ala, D-Val, Lys, Cit or Arg and the α-amino acid in position 34 is Tyr; or the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr and optionally the α-amino acids in positions 8 and 18 are each Nle; or iii. the α-amino acid in position 1 is Aib and at least one further α-amino acid unit has been replaced as follows: the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp, and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr, and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl) , D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys (Fmoc), D-Phe or D-Asn, and/or the α-amino acid in position 13 is Leu, and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His, and/or the α-amino acid in position 23 is 2-(l,3-dithiolane-2-yl)Trρ, and/or the α-amino acid in position 25 and/or in position 26 is His, and/or the α-amino acid in position 27 is Gin or Leu, or the PTH compound is other than PTH(1-84) wherein i. the α-amino acid in position 1 is Tyr, Val, Pro, Asp or Cys; or ii. the α-amino acid in position 2 is Ala, Glu, Leu, Ser or Arg. A PTH compound according to claim 1 or 2 wherein the α-amino acid unit in position 8 and/or the α-amino acid unit in position 18 is replaced by an optionally protected natural or unnatural amino acid residue, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 -ealkoxycarbonyl or optionally substituted Ci-salkyl, C 2 -βalkenyl, C 2 -βalkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acids in positions 8 and 18 are each Nle or each Met (0) and optionally the α-amino acid in position 34 is Tyr; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 34 is Tyr and either the α-amino acid in position 12 is L- or D-Pro, L- or D-Ala, Aib or NMeGly or the α-amino acid in position 23 is Phe, Leu, Nle, Val, Tyr, α-Nal or β-Nal; or the α-amino acids in positions 8 and 18 are each Nle and the α-amino acid in position 2 is D-Val and the α-amino acid in position 34 is D-Tyr; or ii. the α-amino acid in position 8 and/or 18 is Leu, He, Val, Phe or Trp and optionally at least one further α-amino acid unit has been replaced as follows: the α-amino acid in position 1 is Aib and/or the α-amino acid in position 11 is Ser, Lys, Phe, β-Nal, Trp or Tyr, and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl) , D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys (Fmoc) , D-Phe or D-Asn, and/or the α-amino acid in position 13 is Leu, and/or the α-amino acid in position 19 and/or in position 21 is Arg, Lys, Asn or His, and/or the α-amino acid in position 23 is 2-(l,3-dithiolane-2-yl)Trp, and/or the α-amino acid in position 25 and/or in position 26 is His, and/or the α-amino acid in position 27 is Gin or Leu; or iii. the α-amino acid in position 8 and/or 18 is Ala or Ser; or the α-amino acid in position 8 and/or 18 is Leu, and the α-amino acid in position 34 is Tyr; or the PTH compound is other than PTH(1-84) wherein the α-amino acid in position 8 is Met, Met(O), Ala, Val, Leu, He, Ser, Trp, Asn, Gin, Asp, Glu, Lys, Arg, Tyr or Gly and the α-amino acid in position 18 is Leu; or the α-amino acid in position 8 and in position 18 are each Met (0) ; or the α-amino acid in position 8 is Leu and the α-amino acid in position 18 is Met(O); or the PTH compound is other than [Leu 18 ,Tyr 34 ]hPTH(1-84) , [Leu 8 ,Tyr 34 ]hPTH(1-84), [Ile 8 ,Leu 18 ,Tyr 3 ]hPTH(l-84) or [Leu 8 ,Leu 18 ,Tyr 34 ]hPTH(l-84) . A PTH compound having PTH-like activity wherein at least one of the α-amino acid units in the positions 1 to 38 of a PTH sequence is replaced by the α-amino acid unit which is present at the corresponding position in PTHrP, the PTH compound optionally comprising at least one radical selected from a L- or D-α-amino acid, C 2 - 6 alcoxycarbonyl and optionally substituted Ci-salkyl, C 2 -s lkenyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl and attached to the terminal amino group of the PTH compound, and/or at least one radical selected from C 2 - 6 alcoxycarbonyl and optionally substituted Cι_βalkyl, C2-s l enyl, C 2 - 8 alkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl and attached to one or more side chain amino groups of the PTH compound, provided that when the PTH compound is free from D- or L-α-amino acid attached to the N-terminus or from C 2 - 6 alkoxycarbonyl or optionally substituted Cι_salkyl, C 2 -βalkenyl, C -salkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl, it is other than a PTH compound having a naturally occurring α-amino acid sequence; or the PTH compound is other than PTH(1-34) wherein i. the α-amino acid in position 8 and/or 18 is Leu; and/or the α-amino acid in position 11 is Lys; and/or the α-amino acid in position 19 and/or 21 is Arg; and/or the α-amino acid in position 25 and/or 26 is His; and/or the α-amino acid in position 27 is Leu; and optionally at least one further α-amino acid unit has been replaced as follows: the α-amino acid in position 1 is Aib and/or the α-amino acid in position 11 is Ser, Phe, β-Nal, Trp or Tyr, and/or the α-amino acid in position 12 is D-Leu, D-Ile, D-Nle, D-Val, D-Ser, D-Ser(Butyl) , D-Abu, D-Thr, D-Nva, D-Met, D-β-Nal, D-Trp, D-Lys, D-Tyr, D-Lys (Fmoc), D-Phe or D-Asn, and/or the α-amino acid in position 13 is Leu, and/or the α-amino acid in position 19 and/or in position 21 is Lys, Asn or His, and/or the α-amino acid in position 23 is 2-(l,3-dithiolane-2-yl)Trp, and/or the α-amino acid in position 27 is Gin; or ii. the α-amino acid in position 25 in Gin and/or the α-amino acid in position 26 is Asn, the α-amino acid in position 27 being optionally Leu; or the PTH compound is other than [Leu 8 ,Leu 18 ]PTH(l-84) , in free form or in salt or complex form. 7. A PTH compound according to claim 6 wherein at least one of the α-amino acid units in the positions 8 to 11 of a PTH sequence is replaced by the α-amino acid unit which is present at the corresponding position in PTHrP. 8. A PTH compound according to claim 6 wherein at least one of the α-amino acid units in the positions 16 to 19 of a PTH sequence is replaced by the α-amino acid unit which is present at the corresponding position in PTHrP. 9. A PTH compound according to claim 6 wherein at least one of the α-amino acid units in the positions 33 and 34 of a PTH sequence is replaced by the α-amino acid unit which is present at the corresponding position in PTHrP. 10. A PTH compound according to claim 6 wherein one or more α-amino acid units in the remaining positions 1 to 38 is further replaced by a natural or unnatural amino acid unit. 11. A PTH compound according to claim 10 wherein the α-amino acid in position 10 is selected from Gly, Gin, Glu, His, Ser, Thr, Lys and Tyr, and/or the α-amino acid in position 13 is a D- or L-α-amino acid other than Arg, and/or the α-amino acid in position 16 is a D- or L-α-amino acid, •and/or the α-amino acid in position 18 is Gin or Tyr, and/or the α-amino acid in position 19 is selected from Ala, Arg, Val, Tyr, Ser, Lys, Met, His, Gly, Pro, Asn and He, and/or the α-amino acid in position 33 is a D- or L-α-amino acid other than Thr, Phe or Ala. 12. A PTH compound according to claim 6 and 10 which is selected from [Leu 8 , Gin 18 , Thr 33 , Ala 34 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Thr 33 , Ala 34 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gin 18 , Thr 33 , Ala 3 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gln 18 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Ala 19 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Gin 18 ]PTH, [Leu 8 , Asp 10 , Lys 11 , Ala 16 , Gin 18 , Ala 19 ]PTH, [Leu 8 , Ala 16 , Gin 18 , Ala 19 , Thr 33 , Ala 34 ]PTH and [Leu 8 , Asp 10 , Lys 11 , Gin 18 , Thr 33 , Ala 34 ]PTH the PTH compound optionally comprising at least one radical selected from a L- or D-α-amino acid, C 2 -6alcoxycarbonyl and optionally substituted Cι_ 8 alkyl, C -8alkenyl, C2-salkynyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ alkyl and attached to the terminal amino group of the PTH compound, and/or at least one radical selected from C -6 lcoxycarbonyl and optionally substituted Cι_ 8 alkyl, C 2 -8alkenyl, C 2 -8alkynyl, aralkyl, aralkenyl or C3_6cycloalkyl-Cι_ 4 alkyl and attached to one or more side chain amino groups of the PTH compound,in free form or in salt or complex form. 13. A PTH compound according to claim 1 which is a human N-terminal PTH fragment comprising 1-34 to 1-38 amino acid units. 14. A PTH compound according to claim 1 wherein the C-terminus is -COOH, esterified -COOH, -C0NH 2 , mono- or disubstituted -CONH 2 . 15. A .PTH compound selected from [Leu 8 ,Gin 18 ,Thr 33 ,Ala 3 ] -hPTH(1-34)OH [Leu 8 ,Ala 16 ,Gin 18 ,Ala 19 ,Thr 33 ,Ala 3 ]hPTH(1-34)OH [Leu 8 ,Ala 16 ,Gin 18 ,Thr 33 ,Ala 34 ]hPTH (1-34)OH [Leu 8 ,Asp 10 ,Lys 11 ,Gin 18 ]hPTH(1-36)OH [Leu 8 ,Asp 10 ,Lys 11 ,Gin 18 ,Thr 33 ,Ala 3 ]hPTH(1-34)OH [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ,Ala 19 ]hPTH(1-36)OH [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ,Thr 33 ,Ala 34 ]hPTH(1-34)OH [Leu 8 ,Asp 10 ,Lys 11 ,Ala 16 ,Gin 18 ]hPTH(1-36)OH, and [Leu 8 , la 16 ,Gin 18 ,Ala 19 ]hPTH(1-36)OH in free form or in salt or complex form. 16. A process for the production of a desired medium-sized polypeptide in which a fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide having the desired polypeptide linked to the C-terminal thereof, is expressed in bacterial cells. 17. A process according to claim 16 in which the fusion protein comprises a chemically cleavable linker between the gene 55 and the desired polypeptides comprising the amino acid sequences Asp-Pro-Pro or Asn-Gly-Pro. 18. A nucleotide sequence which codes for a fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide and a desired medium-sized polypeptide linked to the C-terminal thereof. 19. A bacterial expression vector comprising a DNA sequence according to claim 18. 20. Bacterial host cells transformed with a DNA sequence according to claim 18, or a bacterial vector according to claim 19. 21. A fusion protein comprising an N-terminal bacteriophage T4 gene 55 polypeptide and a desired medium-sized polypeptide linked to the C-terminal thereof. 22. A process according to claim 16 in which the desired medium-sized polypeptide comprises a PTH polypeptide. 23. A pharmaceutical composition comprising a PTH compound according to claim 1, in free form or in pharmaceutically acceptable salt or complex form, together with a pharmaceutically acceptable diluent or carrier therefor. 24. A PTH compound according to claim 1, in free form or in pharmaceutically acceptable salt or complex form, for use in the preparation of a pharmaceutical composition for use in improving bone formation. 25. A PTH compound according to claim 1, in free form or in pharmaceutically acceptable salt or complex form, for use in the preparation of a pharmaceutical composition in association with a bone resorption inhibitor to improve bone formation. 26. A compound of formula Ilaa or Ilbb ZZ'N - CHY - CW = CH - CHY' - COOH (Ilaa) ZZ'N - CY a Y b " CH 2 - NZ" - CHY' - COOH (Ilbb) wherein each of Z and Z', independently, is H; optionally substituted Ci-galkyl, C 2 - 8 alkenyl, aralkyl, aralkenyl or C 3 _ 6 cycloalkyl-Cι_ 4 alkyl; or a protecting group, at most one of Z and V being a protecting group, Z" is H, Ci-aalkyl or a protecting group each of Y and Y' , independently, is an optionally protec¬ ted side chain of a natural or unnatural α-amino acid, one of Y a and Y^ is hydrogen and the other is an optionally protected side chain of a natural or unnatural α-amino acid or Y a and Y b form together with the carbon atom to which they are attached a C 3 _ 6 cycloalkyl group, and W is halogen or Cι_ 4 alkyl, or and to which t ey are attac e , orm an opt ona y su st tuted aromatic cyclic or heterocyclic residue.

Inventors: ALBERT RAINER, BAUER WILFRIED, BRECKENRIDGE ROBIN, CARDINAUX FRANCOIS, GOMBERT FRANK, GRAM HERMANN, LEWIS IAN, RAMAGE PAUL, SCHNEIDER HELMUT, WAELCHLI RUDOLF, ALBERT, RAINER, BAUER, WILFRIED, BRECKENRIDGE, ROBIN, CARDINAUX, FRANCOIS, GOMBERT, FRANK, GRAM, HERMANN, LEWIS, IAN, RAMAGE, PAUL, SCHNEIDER, HELMUT, WAELCHLI, RUDOLF
Applicants: SANDOZ AG, SANDOZ LTD, SANDOZ LTD., SANDOZ-ERFINDUNGEN VERWALTUNGSGESELLSCHAFT M.B.H., SANDOZ-PATENT-GMBH
Application year: 1993
Main classification: C07K7
IPC codes: A61K38, A61P3, A61P19, A61P43, C07K14, C07K19, C12N1, C12N15, C12P21, C12R1