Abstract:
Disclosed are (1) a DNA containing a DNA segment coding for PACAP38; (2) a precursor protein of PACAP38; (3) a transformant containing a DNA having a DNA segment coding for PACAP38; (4) a method for preparing mature PACAP38 comprising cultivating the transformant described in the above (3), producing and accumulating a protein in a culture, and collecting the resulting protein; and (5) a method for preparing the above polypeptide comprising condensing a partial amino acid or a peptide which can constitute the mature PACAP38, with a residual portion, and removing a protective group if a product has the protective group. The DNA is applied to experimental animals to understand their brain functions, which serves to elucidate human brain functions. PACAP38 provides information about growth and maintenance of rat and human brain nerves, and can also be utilized as therapeutic agents for various neuropathy.

Description:
This is a divisional of copending application Ser. No. 07/540,105 filed on Jun. 10, 1990, now U.S. Pat. No. 5,198,542. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a novel bioactive peptide derived from brain hypothalami, testes or the like, a DNA containing a DNA segment coding for the peptide, a transformant bearing the DNA, and a method for preparing the above peptide by using the transformant. 
     Various hormones secreted by brain hypothalami and hypophyses have been known. Examples thereof include thyrotropin releasing hormone, luteinizing hormone releasing hormone, somatostatin, adrenocorticotropic hormone, growth hormone and prolactin. Action thereof has been well studied. One of the present inventors studied a certain novel bioactive substance of hypothalamic origin other than these hormones based upon adenylate cyclase activity, and consequently discovered a peptide consisting of 38 amino acid residues, which had not been reported till then. The structure thereof was determined and the peptide was named &#34;PACAP38&#34;. 
     The present inventors filed applications for patents (Japanese Patent Application Nos. 1-155791/1990 and 1-284771/1990) on cDNA of sheep PACAP38, and an application for a patent (Japanese Patent Application No. 1-259924/1990) on the partial structure of cDNA of human PACAP38. It was also discovered that the amino acid sequence of the mature portion of sheep PACAP38 was the same as that of human PACAP38, and that some amino acids of the precursors thereof were substituted. 
     However, although the existence of the PACAP38 peptides was confirmed as described above, it is difficult to isolate and purify the peptides and their precursors from hypothalami or the like, because of the necessity of very complicated operations, and that the desired peptides are obtained only in small amounts. It has therefore been desired to provide a method for obtaining the peptides easily and in large amounts. 
     SUMMARY OF THE INVENTION 
     The present inventors have studied mass-production techniques for producing the PACAP38 peptides. As a result, the present inventors have succeeded in isolating a cDNA coding for a PACAP38 peptide from a cDNA library prepared from a messenger RNA of rat brain origin and in determining its nucleotide sequence, from rats as well as from sheep and humans. We discovered that the amino acid sequences of these three kinds of PACAP38 mature proteins are the same, and this has made it possible to obtain the PACAP38 peptides in large amounts by using genetic engineering techniques, thus arriving the present invention. 
     The amino acid sequences of the PACAP38 mature protein is represented by formula (1): ##STR1## 
     In accordance with the present invention, there are provided (1) a DNA containing a DNA segment coding for PACAP 38; (2) a precursor protein of PACAP38; (3 ) a transformant bearing a DNA containing a DNA segment coding for PACAP38; (4) a method for preparing mature PACAP38 comprising cultivating the transformant described in the above (3), producing and accumulating a protein in a culture product, and collecting the resulting protein; and (5) a method for preparing the above polypeptide comprising condensing a partial amino acid or a peptide which can constitute mature PACAP38, with a residual portion, and removing a protective group if a product has the protective group. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified restriction enzyme map of the cDNA coding for a portion of a sheep PACAP38; 
     FIGS. 2-1 to 2--2 show a nucleotide sequence of the cDNA coding for a portion of a sheep PACAP38 precursor and the deduced amino acid sequence of that portion of the sheep PACAP38 precursor; 
     FIG. 3 is a simplified restriction enzyme map of the cDNA coding for a portion of a human PACAP38 precursor; 
     FIGS. 4-1 to 4-2 show a nucleotide sequence of the cDNA coding for a portion of a human PACAP38 precursor and the deduced amino acid sequence of the human PACAP38 precursor; 
     FIG. 5 is a simplified restriction enzyme map of the cDNA coding for a portion of a rat PACAP38 precursor; and 
     FIG. 6 shows a nucleotide sequence of the cDNA coding for a portion of a rat PACAP38 precursor and the deduced amino acid sequence of that rat PACAP38 precursor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the present invention, the DNAs containing the DNA segments coding for sheep PACAP38 include a DNA containing a nucleotide sequence substantially corresponding to formula (2) or (3) and a DNA substantially corresponding to a portion thereof. More preferably the DNA is represented by formula (2) or (3) or a portion thereof. ##STR2## 
     precursors of sheep PACAP38 include a precursor which substantially corresponds to formula (8) or formula (9). Preferably, the precursor is represented by formula (8) or (9). ##STR3## 
     In the present invention, the DNAs containing the DNA segments coding for human PACAP38 include a DNA containing a nucleotide sequence which substantially corresponds to formula (4) or formula (5) and a DNA which substantially corresponds to a portion thereof. More preferably, the DNA is represented by formula (4) or (5) or a portion thereof. ##STR4## 
     Precursors of human PACAP38 include a precursor which substantially corresponds to formula (10) or formula (11). More preferably, the precursor is represented by formula (10) or (11). ##STR5## 
     In the present invention, the DNAs containing the DNA segments coding for rat PACAP38 include a DNA containing a nucleotide sequence which substantially corresponds to formula (6) or formula (7) and a DNA which substantially corresponds to a portion thereof. More preferably, the DNA is represented by formula (6) or (7) or a portion thereof. ##STR6## 
     Precursors of rat PACAP38 include a precursor which substantially corresponds to formula (12) or formula (13). Preferably, the precursor is represented by formula (12) or (13). ##STR7## 
     There is a common portion among sheep-, human- and rat- PACAP38 precursors, which is shown in formula (1&#39;): ##STR8## 
     The term &#34;substantially corresponds&#34; provides for conservative additions, deletions and or substitutions. 
     In the present invention, an expression vector having a DNA containing the nucleotide sequence coding for the precursor protein of PACAP38 or mature PACAP38 can be prepared, for example, by the following process: 
     (i) Messenger RNA (mRNA) is isolated from PACAP38-producing cells, 
     (ii) Single stranded complementary DNA (cDNA) is synthesized from the mRNA, followed by synthesis of double stranded DNA, 
     (iii) The complementary DNA is introduced into a phage or a plasmid, 
     (iv) A host is transformed with the recombinant phage or plasmid thus obtained, 
     (v) After cultivation of the transformant thus obtained, the plasmid or the phage containing the desired DNA is isolated from the transformant by an appropriate method such as hybridization with a DNA probe coding for a portion of PACAP38 or immunoassay using an anti-PACAP38 antibody, 
     (vi) The desired cloned DNA is cut out from the recombinant DNA, and 
     (vii) The cloned DNA or a portion thereof is ligated downstream from a promoter in the expression vector. 
     The mRNA coding for PACAP38 can be obtained from various PACAP38-producing cells such as sheep hypothalami, human hypothalami and testes, or rat hypothalami and testes. 
     Methods for preparing RNA from the PACAP38-producing cells include the guanidine thiocyanate method [J. M. Chirgwin et al., Bio-chemistry 18, 5294 (1979)]. 
     Using the mRNA thus obtained as a template, cDNA is synthesized by use of reverse transcriptase, for example, in accordance with the method of H. Okayama et al. [Molecular and Cellular Biology 2, 161 (1982); ibid. 3, 280 (1983)]. The cDNA thus obtained is introduced into the plasmid. 
     The plasmids into which the cDNA is introduced include, for example, pBR322 [Gene 2, 95 (1977)], pBR325 [Gene 4, 121 (1978)], pUC12 [Gene 19, 259 (1982)] and pUC13 [Gene 19, 259 (1982)], each derived from Escherichia coli, and pUBl10 derived from Bacillus subtilis [Biochemical and Biophysical Research Communication 112, 678 (1983)]. However, any other plasmid can be used as long as it is replicable and growable in the host. The phage vectors into which the cDNA is introduced include, for example, λgtll [R. Young and R. Davis, Proc. Natl. Acad. Sci., U.S.A. 80, 1194 (1983)]. However, any other phage vector can be used as long as it is growable in the host. 
     Methods for introducing the cDNA into the plasmid include, for example, the method described in T. Maniatis et al., Molecular Cloning, Cold Spring Laboratory, p.239 (1982). Methods for introducing the cDNA into the phage vector include, for example, the method of T. V. Hyunh et al. [DNA Cloning, A Practical Approach 1, 49 (1985)]. 
     The plasmid thus obtained is introduced into the appropriate host cells such as Escherichia and Bacillus. 
     Examples of Escherichia described above include Escherichia coli K12DH1 [Proc. Natl. Acad. Sci. U.S.A. 60, 160 (1968)], M103 [Nucleic Acids Research 9, 309 (1981)], JA221 [Journal of Molecular Biology 120, 517, (1978)], HB101 [Journal of Molecular Biology 41, 459 (1969)] and C600 [Genetics 39, 440 (1954)]. 
     Examples of Bacillus described above include Bacillus subtilis MI114 [Gene 24, 255 (1983)] and 207-21 [Journal of Biochemistry 95, 87 (1984)]. 
     Methods for transforming the host with the plasmid include, for example, the calcium chloride method and the calcium chloride/rubidium chloride method described in T. Maniatis et al., Molecular Cloning, Cold Spring Harbor Laboratory, p.249 (1982). 
     When the phage vector is used, for example, the phage vector can be transduced into multiplied Escherichia coli, using the in vitro packaging method. 
     Each of sheep, rat and human cDNA libraries containing sheep, rat and human PACAP38 cDNAs, respectively, can be obtained by the methods described above and the like. 
     Methods for cloning each PACAP38 cDNA from each of the cDNA libraries include, for example, the method of Hyunh et al using phage vector λgtll and an anti-PACAP38 antibody [DNA Cloning, A Practical Approach, p.49 (1985)] and the colony hybridization or plaque hybridization method using a oligonucleotide chemically synthesized on the basis of the amino acid sequence of PACAP38 as a probe [T. Maniatis et al., Molecular Cloning, Cold Spring Harbor Laboratory (1982)]. 
     The PACAP38 cDNA thus cloned is subcloned to, for example, pBR322, pUC12, pUC13, pUC18, pUC19, pUC118, pUC119 or the like to obtain the sheep PACAP38 cDNA, if necessary. 
     The nucleotide sequence of the DNA thus obtained is determined by, for example, the Maxam-Gilbert method [A. M. Maxam and W. Gilbert, Proc. Natl. Acad. Sci., U.S.A. 74, 560 (1977)] or the dideoxy method [J. Messing et al., Nucleic Acids Research 9, 309 (1981)], and the existence of the PACAP38 cDNA is confirmed in comparison with the known amino acid sequence. 
     As described above, a DNA (sheep PACAP38 cDNA) [formula (2)] coding for a portion of the precursor protein of PACAP38 is obtained. 
     The restriction enzyme fragment map of the DNA coding for a portion of the precursor protein of sheep PACAP38 obtained in Example 1, which will hereinafter be described, is shown in FIG. 1. The nucleotide sequence of the cDNA determined by the dideoxy method and the amino acid sequence ascertained from that nucleotide sequence are shown in FIG. 2. 
     The DNA coding for a portion of the precursor protein of sheep PACAP38 cloned as described above can be used as it is, or cut out by digestion with a restriction enzyme if desired, according to the intended use. 
     The region intended to be expressed is cut out from the cloned DNA and ligated downstream from the promoter in a vehicle (vector) suitable for expression, whereby the expression vector can be obtained. 
     The DNA has ATG as a translation initiating codon at the 5&#39;-terminus thereof and may have TAA, TGA or TAG as a translation terminating codon at the 3&#39;-terminus. These translation initiating codon and translation terminating codons may be added by use of an appropriate synthetic DNA adaptor. Further, in order to express the DNA, the promoter is ligated to be upstream thereof. 
     The vectors include the above plasmids derived from Escherichia coli such as pBR322, pBR325, pUC12 and pUC13, the plasmids derived from Bacillus subtilis such as pUB110, pTP5 and pC194, plasmids derived from yeast such as pSH19 and pSH15, bacteriophages such as λphage, and animal viruses such as retroviruses and vaccinia viruses. 
     As the promoter used in the present invention, any promoter can be used as long as it is suitable for expression in the host cell used for the gene expression. 
     When the host cell used for transformation is Escherichia, it is preferable that a trp promoter, a lac promoter, a recA promoter, a λPL promoter, a lpp promoter or the like is used. When the host cell is Bacillus, it is preferable that a SPO1 promoter, a SPO2 promoter, a penP promoter or the like is used. When the host cell is yeast, it is preferred that a PHO5 promoter, a PGK promoter, a GAP promoter, an ADH promoter or the like is used. In particular, it is preferable that the host cell is Escherichia and the promoter is the trp promoter or the λPL promoter. 
     When the host is an animal cell, a SV40-derived promoter, a retrovirus promoter, a metallothionein promoter, a heat shock promoter or the like can be used. 
     The use of an enhancer is also effective for expression. 
     By using a vector containing the DNA coding for the precursor protein of PACAP38 or the mature peptide PACAP38 thus constructed, the transformant is prepared. 
     Examples of host cells include Escherichia, Bacillus, yeast and animal cells. 
     Specific examples of Escherichia and Bacillus include the strains described above. 
     Examples of the yeast described above include Saccharomyces cerevisiae AH22, AH22R - , NA87-11A and DKD-5D. 
     Examples of the animal cells include monkey cell COS-7, Veto, Chinese hamster cell (CHO), mouse L cell and human FL cell. 
     The transformation of Escherichia described above is conducted, for example, according to the method described in Proc. Natl. Acad. Sci. U.S.A., 69, 2110 (1972); Gene, 17, 107 (1982) or the like. 
     The transformation of Bacillus is conducted, for example, according to the method described in Molecular &amp; General Genetics, 168, 111 (1979) or the like. 
     The transformation of the yeast is carried out, for example, according to the method described in Proc. Natl. Acad. Sci. U.S.A., 75, 1929 (1978). 
     The transformation of animal cells is carried out, for example, according to the method described in Virology, 52, 456 (1973). 
     Thus, the transformant transformed with the expression vector containing the DNA coding for a portion of the precursor protein of PACAP38 or the mature peptide (PACAP38) is obtained. 
     When the transformant wherein the host cell is Escherichia or Bacillus is cultivated, a liquid medium is particularly suitable as a medium for cultivation. Carbon sources, nitrogen sources, inorganic compounds and others necessary for growth of the transformants are contained therein. The carbon sources include, for example, glucose, dextrin, soluble starch and sucrose. The nitrogen sources include inorganic or organic materials such as ammonium salts, nitrates, corn steep liquor, peptone, casein, meat extracts, soybean meal and potato extract solution. The inorganic compounds include, for example, calcium chloride, sodium dihydrogenphosphate and magnesium chloride. Further, yeast, vitamins, growth promoting factors and so on may be added thereto. 
     The pH of the medium is preferably about 5 to 8. 
     As the medium for cultivation of Escherichia, it is preferable to use, for example, M9 medium containing glucose and Casamino Acids (Miller, Journal of Experiments in Molecular Genetics, 431-433, Cold Spring Harbor Laboratory, New York, 1972). In order to make the promoter act efficiently, a drug such as 3-indolylacrylic acid may be added thereto, if necessary. 
     When the host cell is Escherichia, the cultivation is usually carried out at about 15° to 43° C. for about 3 to 24 hours, with aeration or agitation if necessary. 
     When the host cell is Bacillus, the cultivation is usually carried out at about 30° to 40° C. for about 6 to 24 hours, with aeration or agitation if necessary. 
     When the yeast transformants are cultivated, there is used, for example, Burkholder minimum medium [K. L. Bostian et al., Proc. Natl. Acad. Sci. U.S.A., 77, 4505 (1980)] as the medium. The pH of the medium is preferably adjusted to about 5 to 8. The cultivation is usually carried out at about 20° to 35° C. for about 24 to 72 hours, with aeration or agitation if necessary. 
     When the animal cell transformants are cultivated, there can be used as the medium, for example, MEM medium containing about 5 to 20% fetal calf serum [Science, 122, 501 (1952)], DMEM medium [Virology, 8, 396 (1959)], RPMI1640 medium [The Journal of the American Medical Association, 199, 519 (1967)] and 199 medium [Proceeding of the Society for the Biological Medicine, 73, 1 (1950)]. The pH is preferably about 6 to 8. The cultivation is usually carried out at about 30° to 40° C. for about 15 to 60 hours, with aeration or agitation if necessary. 
     A portion of the precursor protein of PACAP38 or the mature peptide (PACAP38) can be isolated and purified from the culture described above, for example, by the following method. 
     When a portion of the precursor protein of PACAP38 or the mature peptide (PACAP38) is extracted from the cultivated cells, the cells are collected by a known method after cultivation. Then, the collected cells are suspended in an appropriate buffer solution and disrupted by ultrasonic treatment, lysozyme and/or freeze-thawing. Thereafter, a crude extracted solution of a portion of the precursor protein of sheep PACAP38 or the mature peptide is obtained by centrifugation or filtration. The buffer may contain a protein denaturant such as urea or guanidine hydrochloride, or a surface-active agent such as Triton X-100. 
     When a portion of the procursor protein of PACAP38 or the mature peptide is secreted in the culture solution, the supernatant is separated from the cells by a known method per se after the conclusion of cultivation, and then collected. The separation and purification of a portion of the precursor protein of sheep PACAP38 or the mature peptide contained in the supernatant or the extracted solution thus obtained can be performed by an appropriate combination of known separating and purifying methods per se. These known separating and purifying methods include methods utilizing solubility such as salt precipitation and solvent precipitation, methods mainly utilizing a difference in molecular weight such as dialysis, ultrafiltration, gel filtration and SDS-polyacrylamide gel electrophoresis, methods utilizing a difference in electric charge such as ion-exchange column chromatography, methods utilizing specific affinity such as affinity chromatography, methods utilizing a difference in hydrophobicity such as reverse-phase high performance liquid chromatography and methods utilizing a difference in isoelectric point such as isoelectro focusing electrophoresis. 
     The activity of a portion of the PACAP38 precursor protein or the mature peptide thus formed can be measured by an enzyme immunoassay using a specific antibody. If the products have the vasoconstrictive activity, the activity may be measured as an index. 
     The cells transfected or transformed with the DNA of the present invention can produce a large amount of the precursor protein of PACAP38 or the PACAP38 peptide. The DNA of the present invention is therefore applied to experimental animals to understand its action, particularly brain functions, more particularly brain functions due to hormones. Further, the information thus obtained provides information which serves to elucidate human brain functions. 
     Furthermore, PACAP38 has the rising activity of cAMP. Hence, information about growth and maintenance of rat and human brain nerves can be obtained thereby, and PACAP38 can also be utilized as therapeutic agents for various neuropathy. 
     There were hereinbefore described in detail the cloning of the cDNAs coding for sheep, human and rat PACAP38, the preparation of expression vectors of portions of the sheep, human and rat PACAP38 precursors and mature peptides, the preparation of transformants thereby, the production of portions of PACAP38 precursor proteins and mature peptides by use of the transformants, and the utility thereof. 
     When nucleotides, amino acids and so on are indicated by abbreviations in the specification and drawings, the abbreviations adopted by IUPAC-IUB Commission on Biochemical Nomenclature or commonly used in the art are employed. For example, the following abbreviations are used. When an optical isomer is capable of existing with respect to the amino acids, the L-form is represented unless otherwise specified. 
     DNA: Deoxyribonucleic acid 
     cDNA: Complementary deoxyribonucleic acid 
     A: Adenine 
     T: Thymine 
     G: Guanine 
     C: Cytosine 
     RNA: Ribonucleic acid 
     mRNA: Messenger ribonucleic acid 
     dATP: Deoxyadenosine triphosphate 
     dTTP: Deoxythymidine triphosphate 
     dGTP: Deoxyguanosine triphosphate 
     dCTP: Deoxycytidine triphosphate 
     ATP: Adenosine triphosphate 
     EDTA: Ethylenediaminetetraacetic acid 
     SDS: Sodium dodecyl sulfate 
     BHA: Benzhydrylamine 
     Cl-Z: 2-Chloro-benzyloxycarbonyl 
     Br-Z: 2-Bromo-benzyloxycarbonyl 
     Bzl: Benzyl 
     OBzl: Benzyl ester 
     HOBt: 1-Benzotriazole 
     DCC: N,N&#39;-Dichlorohexylcarbodiimide 
     Gly or G: Glycine 
     Ala or A: Alanine 
     Val or V: Valine 
     Leu or L: Leucine 
     Ile or I: Isoleucine 
     Ser or S: Serine 
     Thr or T: Threonine 
     Cys or C: Cysteine 
     Met or M: Methionine 
     Glu or E: Glutamic acid 
     Asp or D: Aspartic acid 
     Lys or K: Lysine 
     Arg or R: Arginine 
     His or H: Histidine 
     Phe or F: Phenylalanine 
     Tyr or V: Tyrosine 
     Trp or W: Tryptophan 
     Pro or P: Proline 
     Ash or N: Asparagine 
     Gln or Q: Glutamine 
     With respect to the PACAP38 precursor proteins or the mature peptides of the present invention, a portion of the amino acid sequence may be modified, so long as it does not adversely affect biological properties, namely there may be addition, elimination or substitution with other amino acid. 
     The present invention will be described in more detail with the following Reference Examples and Examples. It is understood of course that these Reference Examples and Examples are not intended to limit the scope of the invention. 
     Transformant Escherichia coli DH5α/pOH38P7 obtained in Example 2 described below was deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan (FRI) with the accession number FERM BP-2484 on Jun. 19, 1989. This microorganism was also deposited in the Institute for Fermentation, Osaka, Japan (IFO) with the accession number IFO 14884 on Jun. 15, 1989. 
     Transformant Escherichia coli DH5α/pHT38P8 obtained in Example 3 described below was deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan (FRI) with the accession number FERM BP-2622 on Sep. 28, 1989. This microorganism was also deposited in the Institute for Fermentation, Osaka, Japan (IFO) with the accession number IFO 14953 on Sep. 28, 1989. 
     Transformant Escherichia coli JM109/pRB38P21 obtained in Example 4 described below was deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology, Ministry of International Trade and Industry, Japan (FRI) with the accession number FERM BP-2762 on Feb. 19, 1990. 
     REFERENCE EXAMPLE 1 
     The amino acid sequence of sheep PACAP38 was identical to that of human PACAP38. When PACAP38 (Nat.38p) purified from sheep hypothalami and synthesized PACAP38 (Syn.38p) were allowed to act on rat pituicytes in vitro, an increase in adenylate cyclase activity was observed. The minimum effective amount was 10 -12   M, and it was shown that the activity increased with increasing concentration. 
     Further, similar activity was also observed for synthesized 27-NH 2  [the amino acids situated in the 132nd to 158th positions in FIG. 2, the 1st to 27th positions of mature PACAP38, Syn.27p-NH2 in the following table. The sequence is shown in formula (1&#34;)]. ##STR9## 
     In contrast, the corresponding activity could not be observed for a synthesized porcine VIP (vasoactive intestinal polypeptide). 
     
         ______________________________________Adenylate Cyclase Stimulating Test in Rat Pituicyte Culture        cAMP p mol/ml (M ± SEM)______________________________________Control (Blank)          1.55 ± 0.15Syn.pVIP 10.sup.-12 M          1.35 ± 0.05Syn.pVIP 10.sup.-11 M          1.40 ± 0.00Syn.pVIP 10.sup.-10 M          1.45 ± 0.15Syn.pVIP 10.sup.-9 M          1.75 ± 0.05Syn.pVIP 10.sup.-8 M          2.55 ± 0.25Syn.pVIP 10.sup.-7 M          3.30 ± 0.20Syn.27p-NH.sub.2 10.sup.-12 M          2.05 ± 0.15Syn.27p-NH.sub.2 10.sup.-11 M          2.55 ± 0.15Syn.27p-NH.sub.2 10.sup.-10 M          4.00 ± 0.20Syn.27p-NH.sub.2 10.sup.-9 M          7.90 ± 0.30Syn.27p-NH.sub.2 10.sup.-8 M          9.20 ± 0.00Syn.27p-NH.sub.2 10.sup.-7 M          9.20 ± 0.20Syn.38p 10.sup.-12 M          2.15 ± 0.05Syn.38p 10.sup.-11 M          3.05 ± 0.35Syn.38p 10.sup.-10 M          4.60 ± 0.20Syn.38p 10.sup.-9 M          6.20 ± 0.10Syn.38p 10.sup.-8 M          8.60 ± 0.20Syn.38p 10.sup.-7 M          8.70 ± 0.20Nat.38p 10.sup.-12 M          1.50 ± 0.10Nat.38p 10.sup.-11 M          1.75 ± 0.05Nat.38p 10.sup.-10 M          2.60 ± 0.10Nat.38p 10.sup.-9 M          4.60 ± 0.00Nat.38p 10.sup.-8 M          8.05 ± 0.35Control (Blank)          1.35 ± 0.05______________________________________ 
    
     REFERENCE EXAMPLE 2 
     The materials used in Reference Example 1 were similarly allowed to act on rat pituicytes. As a result, the releasing activity of prolactin (PRL), ACTH and GH was confirmed therein. 
     EXAMPLE 1 
     Preparation of DNA Probe Coding for a Portion of Sheep PACAP38 
     A messenger RNA sequence, was deduced from the amino acid sequence composed of the 1st to the 27th residues of sheep PACAP38, ##STR10## and a DNA probe having the following sequence was chemically synthesized. 
     5&#39;-CACTCTGATGGAATCTTCACAGATAGCTACAGCCGCTATAGAAAGCAAATG-3&#39; and 
     3&#39;-TCGGCGATATCTTTCGTTTACCGACACTTCTTTATGAACCGGCGGCAAGAT-5&#39; 
     The 5&#39;-terminus of this DNA probe was phosphorylated with  32  P by using T4 polynucleotide kinase. The phosphorylated DNA probe was used for screening of the cDNA library. 
     EXAMPLE 2 
     Isolation of Sheep PACAP38 Precursor cDNA and Determination of Nucleotide Sequence Thereof 
     Escherichia coli Y1090 was infected with the above sheep hypothalamus cDNA library (Clontech Labornatories, Inc.) and plated to cause phage plaques to appear. A portion of plague DNA was transferred to a nitrocellulose film according to the method of W. Benton and R. Davis [Science 196, 180-182 (1977)] and hybridized with the DNA probe labeled with  32  P in Example 1. Hybridization was carried out in the absence of formaldehyde at 60° C. Each of 5 clones positive to the hybridization was isolated. Then, a cDNA portion of λOH38P7, which was one of the clones described above, was cut out with EcoRI and recloned into the EcoRI site of plasmid pUC18 to prepare plasmid pOH38P7. By transforming Escherichia coli DH5α with this plasmid, transformant Escherichia coli DH5α/pOH38P7 was obtained. The cDNA portion included in this plasmid was 1.8 Kbp, and the simplified restriction enzyme map thereof is shown in FIG. 1. In the figure,    shows a mature sheep PACAP38 code region. The nucleotide sequence of this cDNA portion was determined by the method of Sanger [Proc. Natl. Acad. Sci. U.S.A. 74, 5463-5467 (1977)]. This nucleotide sequence and a portion of the amino acid sequence of the sheep PACAP38 ,  precursor presumed therefrom are shown in FIG. 2. The region surrounded by     shows the mature peptide portion of sheep PACAP38. 
     EXAMPLE 3 
     Isolation of Human PACAP38 Precursor cDNA and Determination of Nucleotide Sequence Thereof 
     Escherichia coli Y1090 was infected with the above testis cDNA library (Clontech Laboratories, Inc.) and plated to cause phage plaques to appear. A portion of plaque DNA was transferred to a nitrocellulose film according to the method of W. Benton and R. Davis [Science 196, 180-182 (1977)] and hybridized with the DNA probe labeled with  32  P in Example 1. The hybridization was carried out in the absence of formaldehyde at 60° C. Each of 5 clones positive to hybridization was isolated. Then, a cDNA portion of HT38P8 which was one of the clones described above was cut out with EcoRI and recloned into the EcoRI site of plasmid pUC18 to prepare plasmid pHT38P8. By transforming Escherichia coli DH5α with this plasmid, transformant Escherichia coli DH5α/pHT38P8 was obtained The cDNA portion included in this plasmid was 2.3 Kbp, and the simplified restriction enzyme map thereof is shown in FIG. 3. In the figure,    shows a mature human PACAP38 code region. The nucleotide sequence of this cDNA portion was determined by the method of Sanger [Proc. Natl. Acad. Sci. U.S.A. 74, 5463-5467 (1977)]. This nucleotide sequence and a portion of the amino acid sequence of the human PACAP38  precursor deduced therefrom are shown in FIG. 4. The region surrounded by     shows the mature peptide portion of human PACAP38. 
     EXAMPLE 4 
     Isolation of Rat PACAP38 Precursor cDNA and Determination of Nucleotide Sequence Thereof 
     Escherichia coli Y1090 was infected with the above testis cDNA library (Clontech Laboratories, Inc.) and plated to cause phage plaques to appear. A portion of plaque DNA was transferred to a nitrocellulose film according to the method of W. Benton and R. Davis [Science 196, 180-182 (1977)] and hybridized with the DNA probe labeled with  32  P in Example 1. The hybridization was carried out in the absence of formaldehyde at 60° C. Each of 4 clones positive to hybridization was isolated. Then, a cDNA portion of RB38P68 which was one of the clones described above was cut out with EcoRI and recloned into the EcoRI site of plasmid pUC18 to prepare plasmid pRB38P21. By transforming Escherichia coli JM109 with this plasmid, transformant Escherichia coli JM109/pRB38P21 was obtained. The cDNA portion included in this plasmid was 1.2 Kbp, and the simplified restriction enzyme map thereof is shown in FIG. 5. In the figure,    shows a mature rat PACAP38 code region. The nucleotide sequence of this cDNA portion was determined by the method of Sanger [Proc. Natl. Acad. Sci. U.S.A. 74, 5463-5467 (1977)]. This nucleotide sequence and a portion of the amino acid sequence of the rat PACAP38  precursor deduced therefrom are shown in FIG. 6. The region surrounded by     shows the mature peptide portion of rat PACAP38. 
     EXAMPLE 5 
     Synthesis of PACAP38 NH 2   
     PACAP38 NH 2  was synthesized by using 1.04 g (0.5 mmole) of a commercially available p-methyl BHA resin (Applied Biosystems Inc.) and a peptide synthesizer (Model 430A, Applied Biosystems Inc.). 
     A starting amino acid, Boc-Lys(Cl-Z), was activated with HOBt/DCC and then condensed to the resin. Thereafter, the Boc group on the resin was treated with 50% trifluoroacetic acid/methylene chloride to deprotect the amino group. To this free amino group, the following protected amino acids activated with HOBt/DCC were condensed in turn according to the amino acid sequence of PACAP38: ##STR11## After the completion of each reaction, the residual amino groups were acetylated with acetic anhydride to obtain 2.42 g of a protected PACAP38 NH 2  resin. 
     0.51 g of the resulting protected PACAP38 NH 2  resin was treated with 5 ml of hydrogen fluoride in the presence of 0.6 g of p-cresol at 0° C. for 60 minutes, followed by removal of excess hydrogen fluoride by distillation under reduced pressure. The residue was washed twice with 5 ml of ethyl ether, and then extracted with 6 ml of 50% aqueous acetic acid. The insoluble material was removed by filtration and washed with 5 ml of 50% aqueous acetic acid. The filtrate and the washings were combined, and the combined solution was concentrated to 2 to 3 ml. The concentrated solution was applied on a Sephadex LH-20 column (2×90 cm) for elution with 50% acetic acid. The main fractions were collected, followed by removal by distillation under reduced pressure. Then, the residue was dissolved in 100 ml of 0.1% aqueous trifluoroacetic acid. The resulting solution was subjected to a YMC-ODS AM120 S-50 resin column (1.6×7 cm) and eluted by a linear gradient of 0.1% aqueous trifluoroacetic acid and 50% acetonitrile containing 0.1% trifluoroacetic acid. 
     The main fractions were combined, followed by lyophilization. Thus, 60 mg of white powder was obtained. This powder was dissolved in 20 ml of 0.05M aqueous ammonium acetate. The resulting solution was subjected to a CM-Cellulofine resin column (1×6 cm) and eluted by a linear gradient of from 0.05M to 1M ammonium acetate. The main fractions were combined. The combined solution was subjected to a YMC-ODS column (2.6×7 cm) again and eluted by a linear gradient of from 0% to 40% aqueous acetonitrile containing 0.1% trifluoroacetic acid. The fractions of 28% to 30% acetonitrile were collected, followed by lyophilization. Thus, 21.6 mg of white powder was obtained. 
     Anal. for amino acids: Asp 2.90(3), Thr 0.84(1), Set 2.10(3), Glu 2.21(2), Gly 2.00(2), Ala 3.29(3), Val 3.19(3), Met 1.01(1), Ile 0.87(1), Leu 2.19(2), Tyr 3.93(4), Phe 0.92(1), Lys 7.18(7), His 0.96(1), Arg 4.19(4) 
     (M+H) by mass spectrography (SIMS): 4530 
     HPLC elution time: 19.6 minutes 
     Column conditions 
     Column: YMC-ODS (AM-301, S-5 120A) 
     Eluent: 
     A (0.1% aqueous trifluoroacetic acid) 
     B (acetonitrile containing 0.1% trifluoroacetic acid) 
     A linear gradient elution from the eluent A to the eluent B for 50 minutes 
     Flow rate: 1.0 ml/minute 
     EXAMPLE 6 
     Synthesis of PACAP27 NH2 
     PACAP27 NH2 was synthesized by using 1.04 g (0.5 mmole) of a commercially available p-methyl BHA resin (Applied Biosystems Inc.) and a peptide synthesizer (Model 430A, Applied Biosystems Inc.). 
     A starting amino acid, Boc-Leu, was activated with HOBt/DCC and then condensed to the resin. Thereafter, the Boc group on the resin was treated with 50% trifluoroacetic acid/methylene chloride to deprotect the amino group. To this free amino group, the following protected amino acids activated with HOBt/DCC were condensed in turn according to the amino acid sequence of PACAP38 (1-27): ##STR12## After the completion of each reaction, the residual amino groups were acetylated with acetic anhydride to obtain 2.31 g of a protected PACAP27 NH 2  resin. 
     0.50 g of the resulting protected PACAP27 NH 2  resin was treated with 5 ml of hydrogen fluoride in the presence of 0.6 g of p-cresol at 0° C. for 60 minutes, followed by removal of excess hydrogen fluoride by distillation under reduced pressure. The residue was washed twice with 5 ml of ethyl ether, and then extracted with 6 ml of 50% aqueous acetic acid. The insoluble material was removed by filtration and washed with 5 ml of 50% aqueous acetic acid. The filtrate and the washings were combined, and the combined solution was concentrated to 2 to 3 ml. The concentrated solution was applied on a Sephadex LH-20 column (2×90 cm) for elution with 50% acetic acid. The main fractions were collected, followed by lyophilization to obtain 129 mg of white powder. This powder was dissolved in 5 ml of 0.1% aqueous trifluoroacetic acid. The resulting solution was subjected to a TSK-GEL (ODS-120T) column (21.5×300 mm) and eluted with 27% acetonitrile containing 0.1% squeous trifluoroacetic acid. 
     The main fractions were collected, followed by lyophilization. Thus, 17.2 mg of white powder was obtained. Anal. for amino acids: 
     Asp 1.99(2), Thr 0.98(1), Set 2.76(3), Glu 1.25(1), Gly 1.05(1), Ala 3.0 (3), Val 1.56(2), Met 0.78(1), Ile 0.72(1), Leu 1.88(2), Tyr 2.22(3), Phe 0.75(1), Lys 2.73(3), His 1.51(1), Arg 1.94(2) 
     (M+H) by mass spectrography (SIMS): 3145 
     HPLS elution time: 21.2 minutes 
     Column conditions 
     Column: YMC-ODS (AM-301, S-5 120A) 
     Eluent: 
     A (0.1% aqueous trifluoroacetic acid) 
     B (acetonitrile containing 0.1% trifluoroacetic acid) 
     A linear gradient elution from the eluent A to the eluent B for 50 minutes 
     Flow rate: 1.0 ml/minute 
     EXAMPLE 7 
     Using male Wistar rats having a body weight of 350 g under nembutal anesthesia, the hypotensive activity was measured. The resuluts are shown in Table 1. 
     
                       TABLE 1______________________________________   Dosage (n mole/kg)Compound  0.3          1.0       3.0______________________________________PACAP38 NH.sub.2      3.2 ± 1.9                  17.4 ± 2.4                            29.8 ± 3.6     (n = 6)      (n = 6)   (n = 6)PACAP27 NH.sub.2     14.5 ± 3.1                  51.9 ± 9.6                            4.1 (n = 1)     (n = 5)      (n = 5)______________________________________Unit: mm Hg 
    
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