bluuebunny/crossref_metadata_2025 huggingface dataset:
BIOFUNCTIONAL EVALUATION OF A HYDROGEN BOND STABILIZING THE β‐TURN IN THE ACYCLIC PART OF OXYTOCIN
Authors: ROY J. , JOHNSON M. , GAZIS D. , SCHWARTZ I.L.
Published: August 2010

In a continued effort to determine the importance of the hydrogen bonds for stabilization of the biologically active conformation of oxytocin, deamino‐[9‐glycolicamide] oxytocin was synthesized in order to study, in this respect, the hydrogen bond between the peptide N‐H of Gly9and the C=O of Cys6. In this analog the amide linkage between residues at positions 8 and 9 is replaced by an ester. Thus, the residue at position 9 cannot be involved in hydrogen bond formation with the C=O of Cys6. Deamino‐[9‐glycolicamide] oxytocin exhibited 134 ± 13 U/mg and 355 ± 48 U/mg of uterotonic activity in absence and in presence, respectively, of Mg2+, 108 ± 8 U/mg of milk‐ejecting activity, 0.35 ± 0.03 U/mg of pressor activity and 2.5 ± 0.1 U/mg of antidiuretic activity. It is concluded that the hydrogen bond under question is not critical for the conformation required for biofunctional interaction of oxytocin with its receptors in the uterus, mammary gland and other target organs.
ISOLATION AND CHARACTERIZATION OF CYANOGEN BROMIDE FRAGMENTS OF THE A AND B CHAINS OF THE ANTITUMOR TOXIN RICIN D
Authors: BULL HERB , LI STEVEN S. L. , FOWLER ELIZABETH , LIN THOMAS T. S.
Published: August 2010

Both the A and B chains of ricin D consist of four CNBr fragments. These fragments have been isolated from the separated chains of S‐carboxymethylated ricin D obtained from the small bean variety of Ricinus communis. The peptides have been characterized by molecular weight, amino acid composition and amino terminal sequence. A unique order of the peptides is evident for each chain. These sequence data are compared with those obtained for ricin D isolated from the large bean variety (Funatsu et al, 1979; Yoshitake et al., 1978).
COOPERATIVITY IN CALCIUM ION BINDING TO REPETITIVE, CARBOXYLATE‐SERYLPHOSPHATE POLYPEPTIDES AND THE RELATIONSHIP OF THIS PROPERTY TO DENTIN MINERALIZATION
Authors: LEE SANDRA L. , VEIS ARTHUR
Published: August 2010

Analogs of phosphophoryn, a calcium‐binding phosphorylated protein found in mineralized dentin, were synthesized by solid phase peptide synthesis. The dentin phosphophoryn appears to contain some sequence blocks of (Asp‐PhosphoSer)n. As this sequence is difficult to synthesize, polymers of (α‐L‐Glu‐L‐Ser) were prepared. The 30‐peptide, (α‐L‐Glu‐L‐Ser)15, was phosphorylated by reaction with orthophosphoric acid in the presence of trichloroacetonitrile in anhydrous dimethylsulfoxide. Calcium ion binding studies were carried out with both the 30‐peptide and phosphorylated 30‐peptide. The conformation of the original 30‐peptide, (Glu‐Ser)15, was examined, in the presence and absence of calcium ion, by circular dichroism measurements. Purified bovine phosphophoryn, previously studied by the same techniques, was partially dephosphorylated by alkaline phosphatase, and its calcium ion binding properties were determined. Dephosphorylation to 31% of the initial phosphorus content reduced the number of high affinity sites to ˜ 30% of the initial value. However, the stoichiometry of binding indicated that both phosphate and carboxylate groups participate in the high affinity binding and that the binding constant was decreased only slightly. Partial phosphorylation of the 30‐mer raised the calcium binding constant, Ka, from 2.1 times 102 to 3.3 × 103 M‐1 and increased the amount of binding from an electrostatic equivalent number of sites to a stoichiometric equivalent number. Concomitant with binding, there was a transition from random coil to ß‐like structure. These data suggest that the repetitive (Asp‐PhosphoSer)n regions in phosphophoryn and the (Glu‐PhosphoSer)n sequence of the synthetic polymer have special conformations which favor the unidentate binding of calcium to the carboxyl groups and phosphate groups, and which enhance the binding affinities of the carboxyl groups in such sequences in a cooperative fashion.
3‐NITRO‐2‐PYRIDINESULFENYL (Npys) GROUP
Authors: MATSUEDA REI , WALTER RODERICH
Published: August 2010

The novel 3‐nitro‐2‐pyridinesulfenyl (Npys) group, which is useful for the protection and the activation of amino and hydroxyl groups for peptide synthesis, is reported. The Npys group is readily introduced by treatment of amino acids with 3‐nitro‐2‐pyridinesulfenyl chloride. The Npys group is easily removed by treatment with very dilute HCl, e.g. 0.1‐0.2 N HCl in dioxane, but it is resistant to trifluoroacetic acid and 88% formic acid. Npys is also selectively removed under neutral conditions using triphenylphosphine or 2‐pyridinethiol 1‐oxide without affecting benzyloxycarbonyl (Z), tert‐butyloxycarbonyl (Boc), 2‐(4‐biphenylyl) propyl(2) oxycarbonyl (Bpoc), 9‐fluorenylmethyloxycarbonyl (Fmoc), benzyl (Bzl) or tert‐butyl (tBu) protecting groups. The N‐Npys and O‐Npys groups when activated in the presence of RCOOH by the addition of tertiary phosphine form peptide or ester bonds via oxidation‐reduction condensation. The important features of the Npys group are demonstrated through the synthesis of peptides in solution and by solid phase methodology without a formal deprotection procedure. In solid phase synthesis, 4‐(Npys‐oxymethyl) phenylacetic acid is used as the key intermediate for the introduction of the trifluoroacetic acid resistant 4‐(oxymethyl) phenylacetamido linking group to the resin.
PHOTOLABILE MULTI‐DETACHABLE p‐ALKOXYBENZYL ALCOHOL RESIN SUPPORTS FOR PEPTIDE FRAGMENT OR SEMI‐SYNTHESIS
Authors: TAM JAMES P. , DIMARCHI RICHARD D. , MERRIFIELD R.B.
Published: August 2010

Two photolabile multi‐detachable alkoxybenzyl alcohol resins, 2‐[4‐(oxymethyl)phenoxy]propionyl‐resin 4 and 4‐[4‐(oxymethyl)phenoxymethyl]‐3‐nitrobenzamidomethyl‐resin 5 have been synthesized. Bpoc‐peptide attached to resin 4 or 5 when treated with 50% trifluoroacetic acid provided the free, unprotected peptide, but on photolysis gave Bpoc‐peptide p‐hydroxybenzyl ester. Removal of the p‐hydroxybenzyl ester in aqueous base or by oxidative work up gave a protected Bpoc‐peptide suitable for fragment synthesis at its C‐terminus. However, methylation of the ester to Bpoc‐peptide p‐methoxybenzyl ester followed by removal of the Bpoc‐group gave a protected peptide p‐methoxybenzyl ester suitable for fragment coupling at its N‐terminus. The efficacies of these resins were evaluated in the syntheses of a model tetrapeptide and an octapeptide by using Nα‐Bpoc‐, Fmoc‐ and Nps‐amino acids. The use of 2‐thiopyridine with pyridinium hydrochloride as a new and efficient thiolytic reagent for the deprotection of the Nps‐group was studied.
LACTAM RESTRICTION OF PEPTIDE CONFORMATION IN CYCLIC HEXAPEPTIDES WHICH ALTER RUMEN FERMENTATION
Authors: FREIDINGER ROGER M. , VEBER DANIEL F. , HIRSCHMANN RALPH , PAEGE LYNN M.
Published: August 2010

γ‐, δ‐ and ε‐Lactam containing cyclic hexapeptide analogs of cyclo‐(Ala‐Sar)
3 have been prepared by cyclotrimerization. The analogs are covalently bridged between the methyl groups of the alanine and sarcosine residues. Only the δ‐lactam of the S configuration shows the same ability as cyclo‐(Ala‐Sar)3 to inhibit methane production in the fermentation in rumen stomach fluid. The lactam rings of different size therefore offer a sensitive probe of the bioactive conformation of a peptide.
NEW CATEGORY OF VASOPRESSIN RECEPTOR IN THE CENTRAL NERVOUS SYSTEM. Evidence that This Receptor Mediates the Release of a Humoral Factor VIII‐Mobilizing Principle
Authors: CORT J.H. , FISCHMAN A.J. , DODDS W. JEAN , RAND J.H. , SCHWARTZ I.L.
Published: August 2010

Substitution of 9‐D‐Ala‐NH2 for 9‐Gly‐NH2 in the arginine‐vasopressin molecule (AVP) results in suppression of both pressor and antidiuretic activities, but leaves intact and augmented the ability of the analog to increase plasma levels of Factor VIII (FVIII). This change in the biological spectrum of AVP activities is also present when the N‐terminus of the analog is desaminated and when the 1–6 disulfide bridge is converted to a thioether bridge. The vasopressin receptor (VR) involved in the FVIII mobilization response appears to represent a third category of VR which is distinct from the smooth muscle VR and the antidiuretic VR in terms of conformational requirements for hormone‐receptor triggering. By comparing plasma FVIII levels in mixed venous blood after intravenous and various intra‐arterial injections, evidence was adduced that this third (hematological) category of receptor site (HF‐R) is in the central nervous system (CNS). Donor‐receiver experiments were carried out in anesthetized dogs. The donor animal was given the 9‐D‐Ala‐NH2 analog of AVP (dDAlaAVP) by injection into the femoral vein and blood was withdrawn from the internal jugular vein 20 min later; then an injection of 20 ml plasma obtained from this latter sample of donor blood was injected into the femoral vein of a receiver animal. This injection elicited the largest dDAlaAVP‐induced increase in plasma FVIII level yet observed (under all experimental conditions employed to date), strongly suggesting (a) that the brain releases a hitherto unrecognized mobilizing (synthesis‐stimulating and/or releasing) factor for FVIII, (b) that the hematological factor receptor (HF‐R) at which dDAlaAVP acts may be beyond the blood brain barrier and (c) that AVP‐like molecules which act at HF‐R are humoral first messengers in their hematologic function as they are in their actions on smooth muscle and the distal nephron – but at the HF‐R, unlike at the pressor and antidiuretic receptors, these molecules function to effect the release of humoral second messengers which in turn bring about the release and/or increased synthesis of FVIII and plasminogen activator (PA). The 9‐D‐ Ala‐NH2 AVP analog should offer advantage over 1‐desamino‐[8‐D‐Arg]‐VP (dDAVP) in the management of bleeding syndromes related to FVIII deficiency because the undesired side effect of water retention is eliminated.
COMPARATIVE STUDY OF THE NEUROHYPOPHYSEAL HORMONE [8‐ARGININE] VASOPRESSIN AND ITS ANALOG [7‐(3,4‐DEHYDROPROLINE), 8‐ARGININE] VASOPRESSIN IN AQUEOUS SOLUTION: An Examination of the Nonlabile Protons by1H Nuclear Magnetic Resonance Spectroscopy
Authors: WYSSBROD HERMAN R. , FISCHMAN ALAN J. , WITTBOLD WILLIAM M. , SMITH CLARK W. , WALTER RODERICH , SCHWARTZ I.L.
Published: August 2010

[7‐(3, 4‐Dehydroproline), 8‐arginine]vasopressin ([Δ3‐Pro7]AVP), an active analog of the naturally occurring neurohypophyseal hormone [8‐arginine]vasopressin (AVP), was studied in D2O at pD 3.3 and 23° by1H n.m.r. spectroscopy, and chemical shifts (SdLs) and some of the coupling constants for the nonlabile protons (1Hs) were determined and compared to those previously reported by us for AVP in D2O at pD 3.8 and 20° (Wyssbrod et al., 7979a, b). Double‐ resonance difference spectroscopy (Gibbons et al., 1975) was used to reveal positions of certain resonances obscured by overlap with resonances of other1Hs.

Values of δ of corresponding protons in [Δ3‐Pro7]AVP and AVP are quite similar, and the small differences that are observed can be explained on the basis of (a) magnetic anisotropy from the double bond in the Δ3‐prolyl residue, (b) a slight difference in acidity of the samples in the two studies, or (c) uncertainty in the experimentally determined value of δ. Values of δ for the1Hs in the Δ3‐prolyl and prolyl residues in the two peptides are reported.

Our tentative conclusion is that the differences in reported biological activities of [Δ3‐Pro7]AVP and AVP (Botos et al., 1979) are probably not

[Δ3‐PRO7, ARG8] VASOPRESSIN related to a perturbation in the conformational state of the backbone, but that they might be explained, in part, by a change in the conformation of the five‐ membered ring of residue 7 and, in part, by π‐π interaction between the 3‐pyrroline ring of the Δ3‐prolyl residue of [Δ3‐Pro7]AVP and the receptor involved in the antidiuretic response but not the receptor involved in the pressor response, in accordance with the suggestion of Walter (1977) that π‐π interactions might, in some cases, be involved in binding of a peptide to its receptor.
SYNTHESIS OF DERMORPHINS, A NEW CLASS OF OPIATE‐LIKE PEPTIDES
Authors: DE CASTIGLIONE ROBERTO , FAORO FIORENZO , PERSEO GIUSEPPE , PIANI SILVANO
Published: August 2010

H‐Tyr‐D‐Ala‐Phe‐Gly‐Tyr‐Pro‐Ser‐NH2 (dermorphin) and H‐Tyr‐D‐Ala‐Phe‐Gly‐Tyr‐Hyp‐Ser‐NH2 (Hyp6‐dermorphin) are two members of a new class of opiatelike peptides present in the amphibian skin. Their syntheses and that of the L‐Ala2‐analogue of dermorphin have been accomplished by conventional segment condensation in solution.
AMINO ACID COMPOSITION AND SEQUENCE OF DERMORPHIN, A NOVEL OPIATE‐LIKE PEPTIDE FROM THE SKIN OF PHYLLOMEDUSA SAUVAGEI
Authors: MONTECUCCHI PIER CARLO , DE CASTIGLIONE ROBERTO , PIANI SILVANO , GOZZINI LUIGIA , ERSPAMER VITTORIO
Published: August 2010

Dermorphin, a heptapeptide with very potent opiate‐like activity, has been isolated from methanol extracts of the skin of the South American frog Phyllomedusa sauvagei. The amino acid sequence of the peptide is: H‐Tyr‐D‐Ala‐Phe‐Gly‐Tyr‐Pro‐Ser‐NH2. Dermorphin presents striking differences from the known enkephalins; it offers a surprising example of a peptide from Vertebrata containing a D‐amino acid residue in its sequence.
IDENTIFICATION OF DERMORPHIN AND HYP6‐DERMORPHIN IN SKIN EXTRACTS OF THE BRAZILIAN FROG PHYLLOMEDUSA RHODEI
Authors: MONTECUCCHI PIER CARLO , DE CASTIGLIONE ROBERTO , ERSPAMER VITTORIO
Published: August 2010

Methanol extracts of the skin of the Brazilian frog Phyllomedusa rhodei contain approximately equal amounts of dermorphin and its analogue Hyp6‐dermorphin, two opiate‐like heptapeptides. A unique feature of their sequence is the presence of a D‐amino acid residue at position 2. Hyp6‐dermorphin possesses a spectrum of central and peripheral bioactivity very similar to that of dermorphin.
β‐PLEATED SHEETS IN OLIGOPEPTIDE CRYSTALS
Authors: ASHIDA TAMAICHI , TANAKA ISAO , YAMANE TAKASHI
Published: August 2010

Many oligopeptide crystals show the β‐pleated sheet structures. Both parallel and antiparallel chain pleated sheets are found, and also both ideal (flat) and heavily twisted sheets are found. The structural parameters, such as the T (NCα‐C') angles, the torsion angles (φ and ø), the fiber axis periods, the hydrogen bond lengths, and the interchain spacings, are studied. Some of them deviate signifi cantly from those proposed by Pauling & Corey (Proc. Natl. Acad. Sci. US (1953), 39, 253–256). In the heavily twisted sheets, the twists are larger than those in the globular proteins, and each two neighboring chains are almost per pendicular with each other, preserving the β‐sheet type hydrogen bond system. The torsion angles in the twisted sheets are rather close to those of the poly (L‐proline) II helix. It also is discussed that the (NCαC) angles sometimes deviate by almost 5° from the standard value depending on the structures of the main and side chains.
FLUORESCENCE PROPERTIES OF NATIVE AND CHEMICALLY MODIFIED MESENTERICOPEPTIDASE
Authors: RICCHELLI FERNANDA , JORI GIULIO , SHOPOVA MARIA , BOTEVA RAINA , GENOV NICOLAY
Published: August 2010

Studies on the fluorescence properties of native mesentericopeptidase as a function of the temperature and/or in the presence of either neutral or ionic fluorescence quenchers demonstrate that the intrinsic emission of this protein is dominated by a partially exposed tryptophyl residue, which is probably located in a site of high dielectric constant containing positively charged amino acid side chains. One largely exposed tryptophan contributes about 14% of the total emission, whereas one deeply buried tryptophan is virtually non‐fluorescent. The conversion of the active site serine to cysteine and the insertion of either one phenylmethanesulfonyl or one dansyl substituent into the active site induce only subtle differences in the conformational properties with respect to the native protein; in particular, the mutual distances and orientation between the 13 tyrosyl and 3 tryptophyl residues are unaffected, as shown by singletsinglet energy transfer experiments.
ALTERNATIVE REDUCING AGENTS FOR REDUCTIVE METHYLATION OF AMINO GROUPS IN PROTEINS
Authors: GEOGHEGAN KIERAN F. , CABACUNGAN JUDY C. , DIXON HENRY B.F. , FEENEY ROBERT E.
Published: August 2010

Dimethylamine borane and trimethylamine borane were compared with sodium cyanoborohydride as reducing agents for the reductive methylation of amino groups in proteins. Dimethylamine borane performed nearly as well as cyanoborohydride; either reducing agent (15 mM) with 20 mM formaldehyde gave extensive methylation of turkey ovomucoid (5 mg/ml) in 2h at 22°. Trimethyl amine borane gave equivalent levels of methylation only with a higher concen tration of formaldehyde, suggesting that it is an even milder reducing agent than the other two under these conditions. With all three reducing agents, the pH optimum for methylation covered a range of pH 6–9. Methylations should be performed at the lowest possible pH to avoid side reactions of formaldehyde with the protein. Possible effects of these reducing agents on the disulfide bonds of proteins were studied. No reduction of disulfides of turkey ovomucoid was observed using each of the three reducing agents under conditions for methylation.
INFRARED AND LASER‐RAMAN SPECTROSCOPIC STUDIES OF THERMALLY‐INDUCED GLOBULAR PROTEIN GELS
Authors: CLARK A.H. , SAUNDERSON D.H.P. , SUGGETT A.
Published: August 2010

Infrared and laser‐Raman spectroscopy have been used to follow secondary structure changes during the heat‐set gelation of a number of aqueous (D2O) globular protein solutions. Measurements of the infrared Amide I' absorption band around 1650 cm‐1, for BSA gels of varying clarity and texture, have shown that the very considerable variations in network structure underlying these materials are not reflected in obvious differences in secondary structure. In all cases aggregation is accompanied by development of beta‐sheet of a kind common in fibrous protein systems, but for BSA at least this does not appear to vary significantly in amount from one gel type to another. Infrared studies of gels formed from other protein systems have confirmed this tendency for beta‐sheet to develop during aggregation, and the tendency is further substantiated by laser‐Raman evidence which provides the extra information that in most of the examples studied alpha‐helix content simultaneously falls. From these, and other observations, some generalisations are made about the thermally‐induced sol‐to‐gel transformations of globular proteins.
HIGH PRESSURE GEL PERMEATION CHROMATOGRAPHY OF NATIVE PROTEINS ON TSK‐SW COLUMNS
Authors: HIMMEL MICHAEL E. , SQUIRE PHIL G.
Published: August 2010

Twenty‐five proteins in their native state as well as additional materials for the evaluation of column parameters have been submitted to high pressure gel permeation chromatography (GPC) on a TSK G3000 SW column. Our data are compiled from 110 experiments. A new method of treating GPC data has been developed and compared with other methods currently in use. The new method yields lower errors in molecular weights than the others, and by comparison with theoretical plots we were able to attribute the larger errors to curvature of the alternative plots. After studying several methods for characterizing the column, we have concluded that thyroglobulin as well as three or four proteins in the molecular weight range 20,000–300,000, all containing sodium azide, serve to characterize the column with respect to V0, Viand Vt. Extension of this method of analysis to denatured proteins, biopolymers and other polymers is also out lined. Several chromatograms are also presented to illustrate the resolution obtained with columns of this type. Column parameters are compared with values for other packing materials used in GPC.
SYNTHESIS OF 8‐L‐TRYPTOPHAN‐OXYTOCIN AND DETERMINATION OF ONE OF ITS CONFORMATIONAL PARAMETERS
Authors: BODANSZKY MIKLOS , TOLLE JOHN C. , BEDNAREK MARIA A. , SCHILLER PETER W.
Published: August 2010

The hormone analog 8‐l‐tryptophan‐oxytocin was synthesized in solution by stepwise chain lengthening from the C‐terminal residue. Active esters of 9‐fluorenylmethyloxycarbonyl (Fmoc)‐amino acids were used for the incorporation of individual residues and thereby exposure of the tryptophan‐containing intermediates both to acid conditions and to alkylation could be avoided. In a parallel experiment the parent compound, oxytocin, was prepared similarly. The final products were purified by countercurrent distribution.

The presence of tyrosine (donor) and tryptophan (acceptor) in the chain was used for the measurement of the average intramolecular Tyr2‐Trp8 distance by evaluation of intramolecular resonance energy transfer between their fluorescent side chains. Since the 8‐l‐tryptophan analog has high affinity for oxytocin receptors, it is reasonable to assume that its conformation is similar to that of the parent molecule and that in the latter the leucine‐tyrosine distance is of about the same length. The distance of 13.5 Å between the side chains of tyrosine and tryptophan measured in aqueous solution is compatible with the Tyr2‐Leu8 distance determined with molecular models built according to the proposals of Walter for the biologically active conformation of oxytocin.
PREPARATIVE OXIDATIVE CONVERSION OF PROTECTED PEPTIDE Cα‐HYDRAZIDES INTO THE CORRESPONDING ACIDS BY N‐BROMOSUCCINIMIDE
Authors: MEIENHOFER JOHANNES , DZIEDUSZYCKA MARIA , SMULKOWSKI MACIEJ , MAKOFSKE RAYMOND C. , DANHO WALEED
Published: August 2010

A procedure for the preparative, oxidative conversion of protected peptide hydrazides into the corresponding acids by N‐bromosuccinimide is described. Purification was achieved by high performance liquid chromatography on silica gel in chloroform‐alcohol‐acetic acid systems. Average recovery of purified protected peptide acids was over 90%.
β‐LIPOTROPIN: PRIMARY STRUCTURE OF THE HORMONE FROM THE OSTRICH PITUITARY GLAND
Authors: NAUDÉ RYNO J. , CHUNG DAVID , LI CHOH HAO , OELOFSEN WILLEM
Published: August 2010

The amino acid sequence of β‐lipotropin from the ostrich pituitary has been determined. It consists of 79 amino acids. The amino acid 10sequence has been determined as follows: H‐20Ala‐Leu‐Pro‐Pro‐Ala‐Ala‐Met‐Leu‐Pro‐Ala‐30Ala‐Ala‐Glu‐Glu‐Glu‐Glu‐Gly‐Glu‐Glu‐Glu‐40Glu‐Glu‐Gly‐Glu‐Ala‐Glu‐Lys‐Glu‐Asp‐Gly‐50Gly‐Ser‐Tyr‐Arg‐Met‐A rg‐His‐Phe‐Arg‐Trp‐Gln‐60Ala‐Pro‐Leu‐Lys‐Asp‐Lys‐Arg‐Tyr‐Gly‐Gly‐70Phe‐Met‐Ser‐Ser‐Glu‐Arg‐Gly‐Arg‐Ala‐79Pro‐Leu‐Val‐Thr‐Leu‐Phe‐Lys‐Asn‐Ala‐Ile‐Val‐Lys‐Ser‐Ala‐Tyr‐Lys‐Lys‐Gly‐Gln‐OH. When compared with the primary structures of other known β‐lipotropins, the sequence at the NH2‐terminal, β‐melanotropin and β‐endorphin portions of the molecule exhibit considerable variability.
ANALOGS OF AMANIN
Authors: ZANOTTI GIANCARLO , BIRR CHRISTIAN , WIELAND THEODOR
Published: August 2010

Iie3‐amaninamide (3‐R) and its diastereomeric sulfoxide (3‐S) are obtained by oxidation of the bicyclic thioether peptide 2 by hydrogen peroxide in acetic acid. 2 was prepared by an intramolecular Savige‐Fontana reaction of the linear octapeptide tert.‐butylester 4 whose N‐terminal Boc‐Hpi residue on treatment with TFA loses the Boc group and reacts under thioether formation with the released cysteine‐SH. The concomitantly deprotected carboxyl terminus is coupled intramolecularly with the free amino group of the secocompound 5 using the MA or DCCI method, thus forming the homodetic peptide ring. Compounds 3‐R and 3‐S agree very well with analog samples in chiroptical behavior. Thioether 2 and sulfoxide 3‐R exert 50% inhibition of RNA polymerase II (or B) from Drosophila melanogaster in 10–6 M solution whereas Ki of 3‐S is about five times higher.
INHIBITION OF PORCINE ELASTASE II BY CHICKEN OVOINHIBITOR
Authors: VERED M. , GERTLER A. , BURSTEIN Y.
Published: August 2010

Interaction of porcine elastase II with native and modified chicken egg‐white ovoinhibitor was studied by determining the residual activity of the partially inhibited enzyme and by direct measurement of the stoichiometry of interaction using affinity chromatography, electrophoresis and gel filtration. It was found that the chymotrypsin binding site that is not modified by mild oxidation with N‐chlorosuccinimide (Shechter et al., Biochemistry, (1977) 16, 992–997) is capable of binding elastase II as well. The binding of chymotrypsin and elastase II is mutually exclusive and the affinity for chymotrypsin is stronger. Binding of 2 mol trypsin as 1 mol elastase I by ovoinhibitor does not interfere with the binding of elastase II. There is also an indication that the second binding site for chymotrypsin is capable of forming a complex with an additional molecule of elastase II, but the binding is so weak that it could be detected only by electrophoresis.
N‐METHYL PEPTIDES.
Authors: AUBRY A. , VITOUX B. , BOUSSARD G. , MARRAUD M.
Published: August 2010

The model tripeptide tBuCO‐L‐Pro‐Me‐D‐Ala‐MHMe crystallizes in both anhydrous (1) and monohydrated (2) states: 1, monoclinic space group C2 with a = 20.030 (2) Å, b = 5.836 (2) Å, c = 14.958 (3) A and β = 94.11 (1)°; 2, orthorhombic space group P212121 with a = 6.971 (6) Å b = 11.766 (3) Å and c = 22.394 (8) Å Both crystal structures were solved by X‐ray diffraction in order to characterize the influence of water on the molecular structure. The anhydrous molecule accommodates the well‐known, βII‐folded conformation with three trans amide functions and an intramolecular i + 3 → i hydrogen bond. In the hydrated molecule, water is inserted in a loop containing 12 atoms and induces some conformational changes of the peptide backbone.
H N.M.R. STUDIES OF PROTECTED α‐AMINOISOBUTYRIC ACID CONTAINING PEPTIDES
Authors: IQBAL M. , NAGARAJ R. , BALARAM P.
Published: August 2010

The benzylic methylene protons in a large number of benzyloxycarbonyl α‐aminoisobutyric acid (Z‐Aib) containing peptides, show chemical shift nonequivalence. The magnitude of the geminal nonequivalence is correlated with the involvement of the urethane carbonyl group, in an intramolecular hydrogen bond. Studies of the model compounds Z‐Aib‐Aib‐Ala‐NHMe, and Z‐Aib‐Aib‐Aib‐Pro‐OMe clearly establish the presence of intramolecular hydrogen bonds, involving the urethane CO group. In both compounds marked anisochrony of the benzylic methylene protons is demonstrated. In Z‐Aib‐Aib‐Pro‐OMe, where a 4 → 1 hydrogen bonded β‐turn is not possible, the benzylic ‐CH2‐ protons appear as a singlet in CDCl3 and have a very small chemical shift difference in (CD3)2SO. The observation of such nonequivalence is of value in establishing whether the amino terminal Aib‐Pro β‐turn is retained in large peptide fragments of alamethicin.
STABLE ISOLATED SYMMETRICAL ANHYDRIDES OF Nα‐9‐FLUORENYLMETHYLOXYCARBONYLAMINO ACIDS IN SOLID‐PHASE PEPTIDE SYNTHESIS:
Authors: Heimer Edgar P. , Chang Chi‐Deu , Lambros Theodore , Meienhofer Johannes
Published: August 2010

The synthesis and isolation of symmetrical anhydrides of Nα‐9‐fluorenylmethyloxycarbonyl (Fmoc) amino acids using water soluble carbodiimide is described. These compounds were used in a solid phase peptide synthesis of methionine‐enkephalin on a p‐benzyloxybenzyl ester polystyrene 1% divinylbenzene resin support. Homogeneous free pentapeptide was obtained in 42% overall yield. The Fmoc amino acid symmetrical anhydrides were stable during prolonged storage (2 years at 0°) and offer advantages over present “Fmoc solid phase” methods which use anhydrides formed in situ.
IMPROVEMENTS IN THE SYNTHESIS OF SECRETIN BY THE REPETITIVE EXCESS MIXED ANHYDRIDE (REMA) METHOD
Authors: Beyerman H.C. , Kranenburg P. , Schaaper W.M.M. , Voskamp D.
Published: August 2010

Protected secretin, a 27‐peptide amide, was synthesized by the all‐repetitive excess mixed anhydride (REMA) method and purified by preparative reverse‐phase high‐performance liquid chromatography. Highly potent secretin was obtained after deprotection with the aid of HF/anisole and purification by ion‐exchange chromatography. The scope of the REMA‐strategy is discussed in comparison with other strategies.
SYNTHESIS OF THYMOSIN β4
Authors: Wang S.S. , Wang B.S.H. , Chang J.K. , Low T.L.K. , Goldstein A.L.
Published: August 2010

Thymosin β4, an acetylated tritetracontapeptide, was synthesized by an automated solid phase procedure. The synthetic material was shown to be identical to the natural product by physicochemical analyses and bioassays. The proposed structure of the peptide hormone was thus confirmed by a chemical synthesis.
PROTEIN THERMOSTABILITY.
Authors: Merkler David J. , Farrington G. King , Wedler Frederick C.
Published: August 2010

The amino acid compositions of more than 20 enzymes and protein from various closely related mesophilic and thermophilic micro‐organisms (esp. Bacillus) have been used to calculate a variety of macroscopic parameters. These included the hydrophobic index (Hø), the ratio of polar to non‐polar volumes (rho), the ratios of Arg/(Arg + Lys), and (Arg + Lys) or (Glx + Asx) to total amino acids, % H‐bonding amino acids, %α‐helix‐ or β‐sheet‐forming amino acids, the theoretical melting temperature (TmCcalc), the total volume to total amino acid ratio (VR), and the % non‐polar residues (NPS). In contrast to previous similar comparisions with proteins from divergent sources, it was found that thermophilic vs mesophilic proteins from the same genus show correlations between thermostability and increased Hø, decreased rho, and increased Arg/(Arg + Lys), as well as increased α‐index and β‐index. Weaker correlations were seen for VR, TmCalc, aliphatic index, and NPS, all derived from, or related to, Hø. No correlations existed for the other calculated parameters. These results are consistent with recent results of Argos et al. (1979) [Biochemistry 18, 5698–5703] on sequence analyses of glyceraldehyde‐3‐P dehydrogenases, where thermophilic proteins showed multiple amino acid replacements that caused increased internal hydrophobicity and increased external polarity. No trends were observed in any of the parameters calculated from amino acid compositions for crude cytoplasmic protein extracts from mesophilic vs thermophilic Bacilli.
ISOLATION AND PROPERTIES OF β‐ENDORPHIN‐(1–27), Nα‐ACETYL‐β‐ENDORPHIN, CORTICOTROPIN, GAMMA‐LIPOTROPIN AND NEUROPHYSIN FROM EQUINE PITUITARY GLANDS
Authors: Ng Tzi Bun , Chung David , Li Choh Hao
Published: August 2010

Beta‐endorphin‐(1–27), Nα‐acetyl‐beta‐endorphin, corticotropin, gamma‐lipotropin and neurophysin have been isolated from the equine pituitary and characterized.
Evidence for the enzymic degradation of TRH‐related pseudo‐peptides by porcine serum and brain homogenate
Authors: Morier Elisabeth , Han Kia‐Ki , Patsouris Liliane , Moreau Odile , Rips Richard
Published: August 2010

Pseudo‐peptides (pGlu‐His‐amphetamine, pGlu‐His‐Pro‐amphetamine and pGlu‐amphetamine) were subjected to enzymatic degradation by porcine serum and brain homogenate. The enzymic digests were (qualitatively) analyzed by the “Finger‐prints” technique to provide evidence for the presence of free pyroglutamic acid and also quantitatively by HPLC to provide evidence for the presence and yield of free amphetamine. The stability in vitro toward enzymes of serum and brain homogenate of a new type of drug based on the combination of a peptide moiety (TRH) with a non peptide psycho‐tropic moiety (amphetamine) is considered and discussed.
Conformational energy analysis of melanostatin
Authors: ZIMMERMAN S. SCOTT , BAUM ROCKY , SCHERAGA HAROLD A.
Published: August 2010

Conformational energy calculations were carried out on the hypothalamic hormone melanostatin, a tripeptide with the primary structure H‐L‐Pro‐L‐Leu‐Gly‐NH2. The calculated lowest energy conformation was a type II β bend, very similar to that reported in an X‐ray crystal study. This conformation, however, was only one of 109 low‐energy structures (≤ 3 kcal/mol above the global minimum), indicating that the molecule in solution exists as an ensemble of conformations and is very flexible, in agreement with relaxation data from n.m.r. measurements. A statistical analysis yielded an average end‐to‐end distance of 6.8 Å and a bend probability of 0.62, suggesting that, in nonpolar solvents, bend structures predominate within the statistical ensemble. The statistical analysis, however, also yielded a probability of only 0.11 for the occurrence of a 4 → 1 hydrogen bond. Hence, the calculations show that, although bend conformations predominate, bends would be difficult to observe in solution if the experiments were designed only to detect 4 → 1 hydrogen bonds.
Synthesis and properties of equine β‐melanotropin and its naturally occurring des‐Asp analog
Authors: IZDEBSKI JAN , YAMASHIRO DONALD , NG TZI BUN , LI CHOH HAO
Published: August 2010

The syntheses of equine β‐melanotropin and newly isolated des‐Asp1‐β‐melanotropin are described. The syntheses have been accomplished by the solid‐phase method. The lipolytic potency of des‐Asp1‐βe‐MSH is about 5 times higher than that of βe‐MSH.
Ribonuclease inhibitors from the livers of five mammalian species
Authors: BURTON LOUIS E. , FUCCI NOREEN P.
Published: August 2010

Inhibitors of neutral ribonuclease have been purified to homogeneity from beef, pig, sheep, mouse, and rat liver by affinity chromatography on Sepharose‐RNase A with overall yields ranging from 60–80%. Each of the purified inhibitors presents a single band by SDS‐gel electrophoresis; molecular weight estimates by SDS‐gel electrophoresis and by gel filtration are ca. 50000. Each of the inhibitors forms a complex with beef pancreatic RNase A with a molecular weight of ca. 64000, suggestive of 1:1 binding on a molar basis. The inhibitors from liver are very similar in properties and amino acid composition to the previously isolated inhibitor from human placenta (Blackburn et al. (1977) J. Biol Chem.252, 5904) and beef brain (Burton et al. (1980) Int. J. Peptide Protein Res.16, 359). Pig liver offers an alternative to human placenta as a source for an RNase inhibitor of this type (yield, ca. 8 mg/kg of tissue). Immunological similarities were examined using antiserum directed against human placental RNase inhibitor. Cross reactivity of the liver RNase inhibitors with the antiserum raised against placental RNase inhibitor ranged from 15% for mouse RNase inhibitor to as low as 2% for pig and sheep RNase inhibitor.
Amino acid distribution in protein secondary structures
Authors: ARGOS PATRICK , PALAU JAUME
Published: August 2010

The compositional distribution of the twenty amino acids was examined for particular positions within secondary structures (α‐helices, β‐strands, and turns) taken from a 44‐protein sample. Correlation coefficients calculated between positional composition of the amino acids and various of their physico‐chemical characteristics indicated considerable asymmetry in the properties of the residues comprising regions within and adjacent to secondary structures, modes of helix formation, physical parameters most sensitive to the buriedness of residues in β‐strands, and posssible improvements in the accuracy of secondary structure prediction methodologies.
Protein secondary structure
Authors: PALAU JAUME , ARGOS PATRICK , PUIGDOMENECH PERE
Published: August 2010

A secondary structure prediction technique is proposed which includes nucleation site determination through multiplication of conformational preference parameters as well as weighting factors to represent structurally stabilizing short range interactions. The prediction accuracy of the method is calculated using data bases categorized according to the four protein structural classes and with differing assignments of secondary structural regions. The results indicate that nearest neighbor prediction techniques (a) are insensitive to various assignment criteria for the secondary structural spans, (b) have nearly achieved their upper limit of prediction accuracy, and (c) can be somewhat improved through the use of stereochemical weighting factors and conformational parameters derived from the four structural groups.
Interactions between Asp, His, Ser residues within models of the active site of serine proteases
Authors: GENEST M. , PTAK M.
Published: August 2010

Empirical theoretical calculations have been performed on a simplified model of the active site of two serine proteases: α‐chymotrypsin and subtilisin Novo. The stability of the catalytic triad and the hydrogen bond formation between the Asp‐His and His‐Ser pairs have been examined for different protonation states. The results show that the Asp‐His interactions prevail upon the His‐Ser ones. Agreement between calculated configurations and the crystal structure of the site suggests that the presence of other residues near the functional residues is not determinant for the stability of the triad in α‐chymotrypsin. In subtilisin Novo, on the contrary, the presence of the neighbouring residues seems to contribute more largely to the stability. Strong hydrogen bond interactions between the His and Ser residues do not exist in the resting enzymes. Any improvement of the His‐Ser interactions requires large destabilization of the Asp‐His diad. Our results suggest that the mechanism of the proton transfer can occur only from perturbations of the active site structure induced by the presence of the substrate.
Chemical synthesis of urotensin II, a somatostatin‐like peptide in the caudal neurosecretory system of fishes
Authors: CLARK BRIAN R. , DATTILO JAMES , PEARSON DAVID
Published: August 2010

In the goby, Gillichthys mirabilis, urotensin II (a bioactive neuropeptide present in the urophysis of teleost fish) has the dodecapeptide sequence, H2N‐AGTADC‐FWKYCV‐OH, which is homologous with mammalian somatostatin at positions 1, 2 and 7–9. The Merrifield solid phase synthesis of Gillichthys urotensin II (UII) was accomplished by stepwise assembly from the carboxy terminus using Nα‐tert.‐butyloxycarbonyl (Boc) amino acids containing benzyl‐derived groups for protection of side‐chain functionalities. Coupling of amino acids to the growing peptide was mediated by diisopropylcarbodiimide (DIC) in the presence of 1‐hydroxybenzotriazole (HOBt). Residual α‐amino groups remaining after coupling were blocked by acetylation with 1‐acetylimidazole. Crude, synthetic UII was extracted from the HF‐treated, protected peptide‐resin product, reduced with dithiothreitol (DTT), reoxidized at high dilution with O2, and separated into its components using a single, preparative, reverse‐phase HPLC step. The pure, synthetic UII, obtained in 7.6% yield from oxidized crude UII, was indistinguishable from pure, native UII in specific bioactivity, amino acid sequence, and retention time in each of two different HPLC systems.
Tyrosyl interactions at the active site of carboxypeptidase B
Authors: ZISAPEL NAVA , MALLUL YAEL , SOKOLOVSKY MORDECHAI
Published: August 2010

The phosphorescence emission spectra of native carboxypeptidase B and of chemically modified carboxypeptidase B (at arginyl residues) was measured in the presence and absence of peptide and ester substrates (acetyl‐L‐arginine and its hydroxy ester analog: acetyl‐L‐argininic acid). Ester binding did not affect the state of the tyrosyl residue as compared with its state in the substrate‐free enzyme. In the modified enzyme, which is devoid of peptidase activity, binding of the peptide pseudosubstrate did not perturb the state of the tyrosyl residue. The luminescence spectra of Zn2+‐ and Co2+‐carboxypeptidase B in the presence of the metal coordinating ligand cyanide, used to displace the water from the metal coordination sphere, is also described. Cyanide did not affect the luminescence spectra of the active‐site tyrosyl residue in either Zn2+‐or Co2+‐carboxypeptidase, indicating that the tyrosyl residue was not interacting directly with the metal bound water. Hence, the effect of peptide on tyrosyl phosphorescence is not caused by the displacement of the tyrosyl from the coordination sphere, but rather by direct interaction of the peptide bond. The data are consistent with the proposition that the tyrosyl residue participates as a proton donor in amide but not in ester hydrolysis.
Cleavage of aspartyl β‐phenacyl esters by selenophenol under neutral conditions
Authors: MORELL JOHN L. , GAUDREAU PIERRETTE , GROSS ERHARD
Published: August 2010

Neutral selenophenol in DMF accomplished the removal of the β‐phenacyl protecting group of aspartic acid in solution, on the peptide Boc‐Asp(β‐OPac)‐Phe amide and on the resin peptide Boc‐Trp(Nin‐For)‐Met‐Asp(β‐OPac)‐Phe‐ (CCK 30–33) without α, β‐rearrangement.
Dependence of melittin structure on its interaction with multivalent anions and with model membrane systems*
Authors: PODO FRANCA , STROM ROBERTO , CRIFÒ CARLO , ZULAUF MARTIN
Published: August 2010

The conformation and the aggregation state of melittin were investigated in aqueous solutions having different pH values and ionic composition as well as upon interaction with phospholipids. While circular dichroism could only show the existence, in aqueous solution, of either a random‐coil or of a right‐handed helical conformation, high resolution 1H and 13C n.m.r. spectra, together with the results of photon correlation spectroscopy, produced evidence in favour of a number of different well‐defined structural states, depending on anion concentration and charge and on pH. In pure water at neutral pH melittin appeared to exist as a flexible random‐coil monomer; in dilute NaCl a monomeric form was found which was still essentially unordered, but presented a pronounced rigidity of structure, and could be approximated to a prolate ellipsoid. When divalent anions were present (or when high ionic strengths were reached even with monovalent anions) melittin molecules associated into a compact disc‐like tetramer; by 31P n.m.r., correlations could be established between the binding of phosphate ions and the variations in the structure or in the aggregation state of the polypeptide chains. At alkaline pH a helical tetramer was also found, different, however, from that formed in the presence of divalent anions at neutral pH. Upon binding to phospholipids, melittin molecules can be visualized, similarly to what happens in aqueous phosphate solutions, as consisting essentially of a bent right‐handed helix, with a grouping of polar residues along one face of the molecule. The glutamine and lysine residues were strongly immobilized, while there was no n.m.r. evidence for any self‐aggregation of the peptide; the ability of melittin to induce dichromate efflux from phospholipid vesicles was in fact higher when the peptide was in the monomeric state than in the tetrameric one.
Corticotropin inhibiting peptide and a synthetic β‐melanotropin analog inhibit the lipolytic activity of corticotropin and melanotropins
Authors: NG TZI BUN , LI CHOH HAO
Published: August 2010

Lipolysis in isolated rabbit fat cells induced by β‐melanotropin, α‐melanotropin and corticotropin was inhibited by both corticotropin inhibiting peptide and [Gly10]‐β‐melanotropin. Corticotropin inhibiting peptide was a more potent antagonist than [Gly10]‐β‐melanotropin.
Synthesis and properties of human γ‐lipotropin
Authors: IZDEBSKI JAN , YAMASHIRO DONALD , LI CHOH HAO , VITI GIOVANNI
Published: August 2010

The synthesis of human γ‐lipotropin by the solid‐phase method is described. The synthetic product was characterized by Rf in partition chromatography on Sephadex G‐50, paper electrophoresis, polyacrylamide gel electrophoresis, thin‐layer chromatography, HPLC, end group determination, peptide mapping of a tryptic digest, and amino acid analyses of acid and enzymic digests. The synthetic material is identical to natural human γ‐lipotropin when assayed against natural human β‐lipotropin for lipolytic activity.
Component vicinal coupling constants for calculating side‐chain conformations in amino acids
Authors: DE LEEUW F.A.A.M. , ALTONA C.
Published: August 2010

The averaged proton‐proton torsion angles for the three side‐chain rotamers in amino acids are calculated from a statistical analysis of X‐ray structures of side‐chain fragments. In combination with a generalized Karplus equation the limiting coupling constants for the rotamers are calculated. The presently deduced sets are compared with published sets of limiting coupling constants.
Secondary structure prediction of sauvagine, a novel biologically active polypeptide from a frog
Authors: MONTECUCCHI PIER CARLO , GOZZINI LUIGIA
Published: August 2010

The secondary structure of sauvagine has been predicted by the statistical method of Chou & Fasman. The results are compared with those obtained by the analysis of the secondary structure of the corticotropin releasing factor. The pattern of helices and β‐turns within these polypeptides is similar. Thus there is an evolutionary relationship in both sequence and secondary structure between these polypeptides, in accordance with their pharmacological properties.
Evidence that human ceruloplasmin molecule consists of homologous parts
Authors: PROZOROVSKI VLADIMIR N. , RASHKOVETSKI LEONID G. , SHAVLOVSKI MICHAIL M. , VASILIEV VADIM B. , NEIFAKH SOLOMON A.
Published: August 2010

The products of spontaneous and induced proteolysis of human ceruloplasmin (Cp) were studied. Some physico‐chemical properties of the six fragments with electrophoretically determined Mr 13 0000 (F1), 110000 (F2), 66 000 (F3), 48 000 (F4) 22 000 (F5) and 18 000 (F6) were compared. The amino acid compositions and N‐terminal amino acid sequences coincide in F1–F5, but differ from those of F6. Limited tryptic proteolysis of Cp causes the accumulation of polypeptide fragment with Mr 22 000, the N‐terminal primary structure of which is identical to that of F5 produced by spontaneous proteolysis. Electrophoretic fragments of Cp were extracted from polyacrylamide gel, treated with 125I and then studied by peptide mapping with subsequent radioautography. The comparison of the “finger prints” showed the identity of F1 to F2 and F3 and gross similarity between F4 and F1– F3. It also revealed similar peptides in F5 and F6 hydrolyzates and almost perfect matching of the F4 map to the map of F5+ F6 mixture. On the basis of the obtained data general principles of Cp molecular organization are discussed and intramolecular homology is suggested to be a feature of the protein.
Thermal denaturation of human somatotropin, human choriomammotropin and ovine prolactin
Authors: BEWLEY THOMAS A.
Published: August 2010

The thermal denaturation of human choriomammotropin and ovine prolactin in 0.1 M tris‐Cl buffer, pH 8.2, is a simple endothermic process which is at least partially reversible, and does not produce coagulation of the proteins. The transition temperatures suggest fairly stable conformations for these two proteins, but their enthalpies of denaturation are unusually low. The thermal denaturation of human somatotropin begins as an endothermic event with a considerably greater enthalpy of denaturation and a transition temperature higher than that of the other two hormones. However, before the endothermic portion of the denaturation can be completed, the human somatotropin coagulates, producing a powerful exothermic heat flow.
Recognition and utilisation of dansyl‐dipeptides in manual dansyl‐Edman sequencing
Authors: SIMANIS VIESTURS , BARKER DAVID G. , BRUTON CHRIS J.
Published: August 2010

The chromatographic behaviour of the dansyl‐dipeptides likely to be encountered in manual dansyl‐Edman sequencing is presented. The dansyl dipeptides were either encountered in experimental sequencing or chemically synthesised and in some cases both. The advantages of using short hydrolysis times and deliberately generating these dipeptides are discussed.
Dehydro‐enkephalins
Authors: Shimohigashi Yasuyuki , Stammer Charles H.
Published: August 2010

The Gly3residue in Gly2‐ and D‐Ala2‐enkephalins has been replaced by ΔAla3and Ser3in order to examine the effect on binding to the Δ and μ opiate receptors. [D‐Ala2, ΔAla3, Leu5]‐enkephalin maintains most of its receptor binding affinities for both sites. It is suggested that the proper conjunctions of positions 2 and 3 of the enkephalin sequence are important to receptor preference and that position 3 may have a very specific interaction with the Δ receptor. Thein vivoanalgesic and CNS activities of the peptides are also discussed.