bluuebunny/crossref_metadata_2025 huggingface dataset:
ANALYSIS OF O‐H…O HYDROGEN BONDS*
Authors: Mitra Jayati , Ramakrishnan C.
Published: August 2010

Some geometrical parameters associated with the donor and the acceptor end of O‐H…O hydrogen bonds have been analysed. The data consist of 356 hydrogen bonds from reported crystal structures of amino acids, peptides and oligosaccharides. The following conclusions are arrived at:

(a) The most probable range for the hydrogen bond length is between 2.7–2.8 å, the average being 2.76 å. When the donor is a water molecule the distribution is slightly different from the other cases. The average becomes 2.82 å, indicating that O‐H…O hydrogen bonds, where a water molecule acts as a donor, tend to be slightly larger.

(b) The maximum in the distribution for the hydrogen bond angle (H‐O‥ .O) lies in the range 5°–10°, indicating that the O‐H…O hydrogen bonds tend to be slightly nonlinear, a feature similar to that for N‐H…O hydrogen bonds.

(c) For carbonyl type of acceptor groups, the distribution of angle between O‥ .O (or H…O) and C = O extended shows a maximum in the range 50°–60° indicating a directional property towards the lone pair electrons.

In order to study the effect of lone pair orbitals on the direction of orientation of the O‐H group the following parameters connected with the direction of lone pair orbitals are analysed and the main results are:

(d) The elevation of O‥ .O (and H…O) direction from the acceptor plane (plane containing the lone pair orbitals), (ζ), shows a maximum in the range O°–10° indicating that the direction thus tends to lie close to the acceptor plane. For carbonyl acceptor groups, the distribution is uniform up to 30° and many of the larger values of ζ are found to occur for carbonyl acceptor groups only.

(e) The distribution for the angle between the projection Oaccep.…Odonor (and Oaccep.…H) direction on the acceptor plane and the direction of the lone pair orbital (ζ) shows a maximum in the range O°–30°. The distribution is found to be dependent on the number of hydrogen bonds for which the same oxygen atom is the acceptor. The distribution for ζ shows a maximum between 20°–30° for those cases when the oxygen atom is recipient of only one hydrogen bond and the maximum occurs between O°–10° for those cases when the oxygen receives two hydrogen bonds.

(f) The geometry in the limited number of examples where the oxygen is the recipient of three hydrogen bonds is also discussed.
THE SOLID PHASE SYNTHESIS OF PORCINE SECRETIN WITH FULL BIOLOGICAL ACTIVITY
Authors: Hemmasi Bahram , Bayer Ernst
Published: August 2010

The solid phase synthesis of porcine secretin is described. The C‐terminal residue was attached to a polymeric amino support and all the Boc‐amino acids, including Boc‐glutamine, were coupled by a modified carbodiimide method. A preliminary test synthesis showed that the couplings of several amino acids of the N‐terminal section were unsatisfactory. This problem was overcome in the main synthesis by executing all the major reactions twice. Cleavage of the peptide from the resin as well as the removal of all the side chain protecting groups was achieved with liquid HF. The product was purified by ion‐exchange chromatography on SP‐Sephadex to obtain a highly purified heptacosapeptide amide with full biological activity.
PARTIAL SEQUENCES OF HISTONES WITH TUFTSIN ACTIVITY
Authors: Konopinska D. , Nawrocka E. , Siemion I. Z. , Slopek S. , Szymaniec St. , KLonowska E.
Published: August 2010

Tuftsin and six tuftsin analogues with the partial sequences of histones were synthesized by the classical method. Most of these analogues possess a high phagocytosis‐stimulating activity on polymorphonuclear neutrophils from guinea pig.
INTERPRETATION OF THERMAL PERTURBATION SPECTRA OF PROTEINS
Authors: Bello Jake
Published: August 2010

The thermal perturbation difference spectrum of reduced lysozyme has a long wave length extremum at 304 nm at pH 6.15 and a very small extremum at 306 nm at pH 1.5. These results differ from those of Leach & Smith (1972), which showed an extremum at 293 nm, the same as for model tryptophyl compounds. Our result may arise from a conformational difference between the two sample temperatures. The interpretation of thermal perturbation spectra of proteins is discussed. Contributions from thermally induced concentration differences, buried chromophores, and chromophores in crevices are considered in the interpretation of the thermal perturbation spectrum of bovine serum albumin.

It is suggested that chromophores in pauci‐aqueous crevices may appear buried toward thermal perturbation spectroscopy but accessible toward solvent perturbation and chemical reagents.
STUDIES ON CYTOCHROME C:
Authors: Moroder Luis , Borin Gianfranco , Filippi Bruno , Stivanello Diego , Marchiori Fernando
Published: August 2010

This paper is part of a series on synthesis of suitably protected peptides covering the 66–104 sequence of horse heart cytochrome c. It describes the preparation, by conventional procedures, of a partially protected Nα‐benzyloxycarbonyl‐undecapeptide hydrazide corresponding to the sequence from 66 to 76 (Fragment F), which represents a building block for the synthesis of the entire 66 – 104 sequence.

Moreover, the preparation is described of a partially protected pentadecapeptide corresponding to the sequence region 66 to 80, which represents the key peptide for the semisynthesis of the same COOH‐terminal sequence utilizing the natural 81 – 104 N‐trifluoroacetylated CNBr fragment.
ASYMMETRIC HYDROGENATION OF UNSATURATED PEPTIDES
Authors: Pieroni O. , Bacciola D. , Fissi A. , Felicioli R. A. , Balestreri E.
Published: August 2010

Eleven unsaturated peptides, containing one or two dehydro‐phenylalanyl (dehydro‐Phe) residues and a C‐terminal L‐amino acid have been hydrogenated in the presence of palladium‐on‐charcoal.

Hydrolysis of the saturated peptides thus obtained gave optically active phenylalanine showing the occurrence of asymmetric induction during the hydrogenation.

Both mono‐unsaturated dipeptides and doubly unsaturated tripeptides with L‐Glu, L‐Leu and L‐Val as chiral end‐group afforded L‐Phe in 40–50% optical yield. In the case of the tripeptide N‐acetyl‐(dehydro‐Phe)‐(dehydro‐Tyr)‐L‐Glu the asymmetric induction was higher (70%) for the unsaturated residue which is farther from the chiral end‐group along the peptide chain.

The results are discussed on the bases of Prelog rule and the rigid dissymmetric conformation of the dehydropeptides in solution.
ISOLATION AND CHARACTERIZATION OF HIGHLY PURIFIED ALPHA‐1‐ANTITRYPSIN
Authors: Plancot Marie‐Therese , Delacourte Andre , Han Kia‐Ki , Dautrevaux Michel , Biserte Gerard
Published: August 2010

Highly purified human alpha‐1‐antitrypsin (phenotype MM) was obtained by an original method of preparative electrophoresis. The criteria of homogeneity were assured by one arc in crossed immunoelectrophoresis and one band on polyacrylamide gel. A unique N‐terminal amino acid (pyroglutamic acid) and a unique C‐terminal residue (lysine) were identified. Determined by gel electrophoresis, its molecular weight was 47,000 daltons.
PREPARATION OF CARBOXYL‐TERMINAL TRYPTIC PEPTIDES FROM PROTEINS BY CLEAVAGE AT ARGININE
Authors: Fong Shao‐Ling , Hargrave Paul A.
Published: August 2010

A method has been developed for selectively preparing the carboxyl‐terminal tryptic peptide of proteins by cleavage at arginyl residues. The succinylated protein is digested with trypsin and the peptides produced are maleylated. Maleylated peptides are then submitted to cation‐exchange chromatography in urea at low pH and ionic strength. Arginine‐containing peptides are retained by the resin. The carboxyl‐terminal peptide emerges unretarded and in pure form. This method has been applied to four proteins of known sequence. Yields as high as 88% have been obtained.
TABLE OF AMINO ACID REPLACEMENTS IN PROTEINS POSSIBLE AS A RESULT OF ONE‐POINT MUTATIONS
Authors: MikeŠ Otakar , Rychlik Ivan , ŠOrm FrantiŠEk
Published: August 2010

A Table of amino acid replacements based on one‐point mutations is presented. For each amino acid replacement the number of mutations of various codons resulting in this mutation is recorded.
PHYSICAL PROPERTIES OF TAMM‐HORSFALL GLYCOPROTEIN AND ITS GLYCOPOLYPEPTIDE
Authors: Hamlin Larry M. , Fish Wayne W.
Published: August 2010

The molecular weight of the constituent glycopolypeptide chain of T‐H glycoprotein was determined by sedimentation equilibrium under two entirely different sets of denaturing conditions. For both sets of denaturing conditions, the average molecular weight estimated for T‐H glycopoly peptide was 74,000. The gel chromatographic behavior in 6 Mguanidium chloride of T‐H glycopoly peptide with disulfide bonds intact as compared with its gel chromatographic behavior with disulfide bonds broken indicated that the glycopolypeptide is highly constrained by intrachain disulfide bonds.
CONFORMATIONAL STABILITY OF A SNAKE CARDIOTOXIN
Authors: Hung Mien‐Chie , Chen Yee‐Hsiung
Published: August 2010

A snake cardiotoxin from the venom of the Formosan cobra, Naja naja atra, is a basic polypeptide. The protein can be denatured in 6.0 M guanidine hydrochloride or at elevated temperatures. Its conformation remains virtually the same in solvents of lower polarity than water such as 1, 2‐ethanediol or 1‐propanol and 1, 2‐ethanediol (1:1 v/v). The circular dichroism spectrum is atypical in water in that the peptide chromophores show a small negative CD band at 214 nm and a large positive one at 195 nm. To some extent the CD pattern resembles that of the β‐form but differs in specific positions and magnitudes. Considering that the theoretical CD of the reverse β‐bend and the characteristics of model polypeptides in β‐form manifest a similar pattern, we suggest that cobra cardiotoxin is rich in β structure including β pleated‐sheets and β reverseturns.
CONFORMATIONS OF PROLINE‐CONTAINING CYCLIC PEPTIDES:
Authors: Hollosi M. , Radics L. , Wieland Th.
Published: August 2010

As inferred from 13C, 1H n.m.r. data, CD measurements and ion‐binding experiments, the title molecule can assume two major C2 symmetric conformations. One of these has an all‐trans X‐Pro peptide backbone with two 1 4 intramolecular H‐bonds and represents the predominant (≥ 95%) form in D2O and nonpolar (CD3CN) solvents. Stabilized by specific solvent‐solute interactions, the other conformer becomes competitive (45%) in DMSO solution. It is shown to possess a four‐cis X‐Pro skeleton and no intramolecular H‐bonds. The Mg++ complex of the cyclic peptide in CD3CN is again C2 symmetric and its formation proceeds via a slow trans → cis isomerization of two X‐Pro peptide bonds.
REACTIVITY OF SULFHYDRYL GROUP IN PEPTIDES AND POLYPEPTIDES WITH p‐NITROPHENYLACETATE. S to N ACYL SHIFT IN CYSTEINE
Authors: Trudelle Yves , Caille Anita
Published: August 2010

The activity of poly (Cys‐Ser‐Phe‐Glu‐Glu) and related polypeptides as models of cysteine‐proteases towards p‐nitrophenylacetate was studied. The reaction leads to the formation of an S‐acetylated form which proved to be quite stable, except at very high pH values. The presence of imidazole groups in the neighbourhood of sulfhydryl functions seems to result in an enhancement of the activity, which we attributed to a cooperative interaction. However, this interaction has no effect upon the S‐deacylation rate. In the case of cysteine we found that the reaction with NPA occurred through a S to N acyl shift. Our results lead us to suggest that, unless convincing proofs of deacylation are given, the various models of cysteine‐proteases studied so far do not behave as “true catalysts”.
MODEL POLYPEPTIDES FOR α‐HELIX COILED COIL PROTEINS:
Authors: Treiber L. R. , Wong W. Mai , Shen M. E. , Walton Dr.A. G.
Published: August 2010

A polyheptapeptide poly (Ala‐Leu‐Lys‐Glu‐Ala2‐Glu) has been synthesized by polymerization of the blocked heptamer and by sequential synthesis. The former method yields molecular weights up to 40, 000, the latter a product of rather uniform D.P = 25, i.e. a molecular weight Mr= 18, 250. The polypeptide was designed to have a repeat sequence of hydrophobic residues of the type expected in α‐keratin and in tropomyosin and was designed to optimize hydrophobic bonding between two chains.

Preliminary characterization indicates that in aqueous solution the polypeptides are random at all pH, but high molecular weight material shows a small amount (up to 20%) of α‐helix. However, crystallization of the material from certain solvents and solvent mixtures including chloroform I trifluoroacetic acid and hexafluoroisopropanol, produces α‐helical material which in some cases is crystalline.

Electron microscopy of the crystalline material shows lozenge‐shaped crystals of about 1 μ in maximum side and ˜ 300 Å thick. Diffuse electron diffraction has been obtained with d = 16.1 Å. The hexafluoroisopropanol‐precipitated material, which is α‐helical by infrared spectroscopy and film circular dichroism, gives a diffuse X‐ray diffraction pattern with d = 5.1 å and d = 2.5 å. Attempts to orient the material caused distortion toβ‐sheet form. The diffraction studies are consistent with an α‐helix coiled coil and a tentative cell packing arrangement is described.
COMPARATIVE CONFORMATIONAL ANALYSIS OF HUMAN CHORIOMAMMOTROPIN AND SOMATOTROPIN FROM SEVERAL SPECIES
Authors: Holladay Leslie A. , Puett David
Published: August 2010

The conformations of porcine somatotropin and human choriomammotropin have been studied using circular dichroism (CD) and the results compared with spectra of human, murine, ovine, and bovine somatotropin. The far ultraviolet CD spectra of the six proteins were similar, and each spectrum was analyzed using constrained linear least squares. The following average percentages of α‐helicity, β‐structure, and aperiodic (nonhelical) conformation were obtained: 57, 6, and 37, respectively, based on a standard protein reference set, and 42, 22, and 36, respectively, based on poly‐L‐lysine as reference. Thus, the estimated secondary structure is strongly dependent upon the reference data used. Interestingly for these similar proteins, it appears that over 60% of the residues are part of ordered secondary structure and less than 40% are in an aperiodic conformation. The near ultraviolet CD spectra of these hormones were similar in many respects, although certain significant differences were observed, particularly in the sign of various extrema. These spectral differences probably reflect non‐identical microenvironments of the aromatics and disulfides, arising from differences both in amino acid sequence and local conformation.
IMMUNOELECTROPHORETIC QUANTITATION OF ANTITHROMBIN III:
Authors: Grimmer ø. , Fagerhol M. K.
Published: August 2010

Antithrombin III (AT‐III), being an α2‐globulin, will have an electrophoretic mobility in the presence of heparin like prealbumin in agarose gels. This phenomenon was utilized to quantitate AT‐III from serum and plasma by electroimmunodiffusion (EID) for 90 min in agarose gels containing 75 USP units of heparin/ml gel. The method permits a rapid quantitation of AT‐III from serum, citrated plasma and EDTA plasma, and a positive correlation was observed between these values and those obtained by single radial immunodiffusion (SRI). This is in contrast to quantitation of AT‐III by EID in gels containing no heparin where the values for plasma showed poor correlation with those obtained by SRI.
THE PRIMARY STRUCTURE OF HUMAN UROGASTRONE
Authors: Gregory H. , Preston B.M.
Published: August 2010

Urogastrone is a potent inhibitor of gastric acid secretion which is present in human urine. Its existence has been known for over 30 years but it has only recently been isolated in a sufficiently pure form for detailed structural studies to be undertaken. Two separate polypeptides β‐ and γ‐urogastrone were isolated. The structures were established by carrying out enzymic degradations of S‐carboxymethyl and S‐carboxamidomethyl derivatives with trypsin, chymotrypsin, thermolysin and a protease derived from the fungus Armillaria mellea. Sequences of the smaller peptides thus obtained were determined by the dansyl Edman method. Partial acid hydrolysis of urogastrone itself gave fragments containing single intact disulphide bonds, and oxidation then allowed the direction of individual bonds to be established. β‐Urogastrone was shown to be a 53‐amino acid residue polypeptide containing three disulphide bonds, and γ‐urogastrone had an identical sequence but lacked the C‐terminal arginine residue.

Urogastrone was subsequently found to be structurally related to mouse epidermal growth factor in that 37 of the 53 residues were commonly located in each polypeptide. Furthermore, as both peptides had similar effects upon gastric acid secretion and upon epidermal growth, urogastrone was also a human epidermal growth factor. The 16 variable residues were spread across the molecule, all apart from two were compatible with single base changes in the triplet codons, and the overall effect was to make urogastrone more acidic than EGF. The smallest biologically active unit has not been defined but at least six residues can be removed from the C‐terminus without causing a reduction in potency.
THE INFLUENCE OF ESTERIFICATION OF CARBOXYL GROUPS OF RIBONUCLEASE‐A ON ITS STRUCTURE AND IMMUNOLOGICAL ACTIVITY
Authors: Acharya A. Seetharama , Manjula B. N. , Murthy G. Satyanarayana , Vithayathil Paul J.
Published: August 2010

The effect of modification of carboxyl groups of Ribonuclease‐Aa on the enzymatic activity and the antigenic structure of the protein has been studied. Modification of four of the eleven free carboxyl groups of the protein by esterification in anhydrous methanol/0.1 M hydrochloric acid resulted in nearly 80% loss in enzymatic activity but had very little influence on the antigenic structure of the protein. Further increases in the modification of the carboxyl groups caused a progressive loss in immunological activity, and the fully methylated RNase‐A exhibited nearly 30% immunological activity. Concomitant with this change in the antigenic structure of the protein, the ability of the molecule to complement with RNase‐S‐protein increased, clearly indicating the unfolding of the peptide “tail” from the remainder of the molecule. The susceptibility to proteolysis, accessibility of methionine residues for orthobenzoquinone reaction and the loss in immunological activity of the more extensively esterified derivatives of RNase‐A are suggestive of the more flexible conformation of these derivatives as compared with the compact native conformation. The fact that even the fully methylated RNase‐A retains nearly 30% of its immunological activity suggested that the modified protein contained antibody recognizable residual native structure, which presumably accommodates some antigenic determinants.
STUDIES OF THE AFFINITY OF HUMAN SERUM ALBUMIN FOR BINDING OF BILIRUBIN AT DIFFERENT TEMPERATURES AND IONIC STRENGTH
Authors: Jacobsen JøRgen
Published: August 2010

The association constants for the binding of bilirubin to human serum albumin (HSA) have been determined at four different temperatures by measurements of the rate of the peroxidase catalyzed oxidation of unbound bilirubin. The change of enthalpy is determined from a van't Hoff plot (ln Kass versus 1/T) to about —13.5 kcal/mol. ΔGd̀ is calculated from the binding constants, and ΔSd̀ is obtained from: ΔGd̀=ΔHd̀— TΔSd̀. The results show that the large negative ΔGd̀ (— 11 kcal/mol) for binding of bilirubin to HSA is a consequence of the negative ΔHd̀. The entropy was found to be about — 8.5 cal/mol/degree and tends to diminish the numerical value of ΔGd̀.

The binding constant has also been determined at varying ionic strength. The results show a decrease in binding for increasing salt concentration.

The data from the two sets of experiments suggest that hydrogen bonds and salt linkages rather than hydrophobic interactions are the main factor in the binding of bilirubin to its primary site on HSA.
AN ALTERNATIVE SYNTHESIS OF [7‐(THIAZOLIDINE‐4‐CARBOXYLIC ACID)]‐OXYTOCIN
Authors: Barber Mary , Jones John H.
Published: August 2010

An alternative synthesis of [7‐(thiazolidine‐4‐carboxylic acid)]‐oxytocin by a 6 + 3 route using a hexapeptide with a preformed disulphide bridge is outlined.
CONFORMATIONAL STUDIES ON SEQUENTIAL POLYPEPTIDES:
Authors: Tamburro A.M. , Scatturin A. , Del Pra A.
Published: August 2010

The conformational properties of (Pro‐Phe‐Gly)n and (Phe‐Pro‐Gly)n were investigated both in the solid state and in solution. In solid state X‐ray diffraction patterns seem to indicate that (Pro‐Phe‐Gly)n assumes a single chain triple helical structure. In solution, by circular dichroism studies, it was possible to show the existence of β‐bends in the presence of ethylene glycol. Similar studies carried out on (Phe‐Pro‐Gly)n showed no collagen or polyproline 11–like structure in the solid state. In solution the β‐bend formation was apparent in all the solvent systems studied.
DESIGN OF A PHOTOAFFINITY LABEL FOR THE HORMONE BINDING SITE OF NEUROPHYSIN
Authors: Klausner Yakir S. , Mccormick William M. , Chaiken Irwin M.
Published: August 2010

The photolabile peptide, L‐methionyl‐L‐tyrosyl‐p‐azido‐L‐phenylalaninamide, was synthesized by solution methods. This peptide, as well as the analogous species containing tritiated methionine, were found to bind reversibly and specifically, in the dark, to bovine neurophysin II. The dissociation constant, stoichiometry, and pH‐dependence of this noncovalent interaction are typical of those properties for hormone (oxytocin) and hormone‐like ligand binding to neurophysin II. Under photolytic conditions, methionyl‐tyrosyl‐p‐azidophenylalaninamide causes irreversible inhibition of the noncovalent ligand binding activity of neurophysin II. This inactivation was achieved to the extent of about 90%. Both the dark and light (photolytic) interactions of the photolabile peptide with neurophysin II indicate its reaction at the hormone binding site of the protein and thus its potential use to identify amino acid residues at this site by covalent photoaffinity labelling.
THE «ANOMALOUS» 304nm EXTREMUM IN THE THERMAL PERTURBATION OF TRYPTOPHAN
Authors: Bello Jake , Bello Helene R.
Published: August 2010

Thermal perturbation spectra of α‐chymotrypsinogen with and without the fluorescence quencher Eu(NO3)3 show that the «anomalous» 305 nm extremum (presumed to arise from tryptophan residues) is not a fluorescence artifact. A similar result was obtained for Nα‐acetyltryptophan amide in 13.6 M potassium formate.
A SIMPLE MODEL FOR PROTEIN THERMAL DENATURATION*
Authors: Bandekar Jagdeesh
Published: August 2010

Whether proteins denature in an all‐or‐none fashion or in a continuous fashion is as yet an unresolved problem. The all‐or‐none process implies that while the process of denaturation is going on, only two kinds of protein molecules can exist. One is completely unchanged and the other is altered. The altered protein molecules are indistinguishable. Underlying the ‘continuum’ models is the assumption that all the chains in a protein globule undergo similar changes so that it is enough to consider a single chain.
CHAINS OF ALTERNATING SULFUR AND π‐BONDED ATOMS IN EIGHT SMALL PROTEINS
Authors: Morgan Richard S. , Tatsch Clinton E. , Gushard Robert H. , Mcadon John M. , Warme Paul K.
Published: August 2010

This paper demonstrates the existence of regions in eight small globular proteins in which the side chains of sulfur‐containing amino acids (cysteine and methionine) alternate in space with side chains of aromatic amino acids (histidine, phenylalanine, tryptophan and tyrosine). The proteins are: rubredoxin, high potential iron protein, cytochrome c, flavodoxin, deoxyhemoglobin, trypsin inhibitor, ribonuclease‐S, and lysozyme. The sulfur‐φ‐bonded ‘chains’ involve a minimum of five and a maximum of 10 amino acids, and contain the most polarizable atoms within proteins. S‐φ‐chains give extra stability to the folding of proteins; they may also afford paths for the step‐wise movement of electrons.
SOLID‐PHASE PEPTIDE SYNTHESIS USING MILD BASE CLEAVAGE OF NαFLUORENYLMETHYLOXYCARBONYLAMINO ACIDS, EXEMPLIFIED BY A SYNTHESIS OF DIHYDROSOMATOSTATIN
Authors: Chang Chi‐Deu , Meienhofer Johannes
Published: August 2010

N
α‐9‐Fluorenylmethyloxycarbonyl (Fmoc) amino acids will be of advantage in solid phase peptide synthesis. The Fmoc‐group is quantitatively cleaved by mild base (piperidine). This permits the use of tert‐butyl‐type side chain blocking and of peptide‐to‐resin linkage cleavable by mild acidolysis. Side reactions arising from repetitive acid deprotection and final HF cleavage in contemporary solid phase synthesis are avoided. Fully bioactive and homogeneous dihydrosomatostatin was obtained in 53% overall yield.
β‐ENDORPHIN: SYNTHESIS AND ANALGESIC ACTIVITY OF SEVERAL ANALOGS MODIFIED IN POSITIONS 2 AND 5
Authors: Yamashiro Donald , Li Choh Hao , Tseng Liang‐Fu , Loh Horace H.
Published: August 2010

The solid‐phase syntheses of [Sar2]‐, [Ala2]‐, [D‐Leu2]‐, [D‐Lys2]‐β‐ endorphins and [Pro5]‐, [Leu5]‐, [D‐Leu5]‐, [D‐Ala2, D‐Leu5]‐β‐endorphins are described. The synthetic peptides were purified by chromatography on carboxymethylcellulose and partition chromatography on Sephadex G‐50. They were characterized by partition chromatography on agarose, thin‐layer chromatography, paper electrophoresis, and amino acid analyses of acid and enzymic hydrolysates. Bioassay of the synthetic analogs for analgesic activity by the tail‐flick method showed the D‐Leu2analog to be 48% as potent as βh‐endorphin while the Ala2, D‐Lys2, Leu5, and [D‐Ala2, D‐Leu5] analogs were 8 to 17% as active. The Sar2, D‐Leu5, and Pro5analogs were less than 1% as potent.
STUDIES ON TRYPSIN INHIBITORS
Authors: Tomatis Roberto , Guggi Augusto , Salvadori Severo , Periotto Vittorio , Rocchi Raniero
Published: August 2010

The synthesis by fragment condensation of protected peptides corresponding to the amino acid sequences 15–35, 25–52 and 15–52 of porcine pancreatic secretory trypsin inhibitor II (Kazal type) is described. The Rudinger modification of the azide procedure was used in the fragment coupling steps.

The tert‐butyloxycarbonylheptapeptide hydrazide (sequence 22–28) was reacted with the heptapeptide methyl ester free base (sequence 29–35) and the resulting tert‐butyloxycarbonyltetradecapeptide methyl ester after selective deprotection, coupled with the benzyloxycarbonylheptapeptide hydrazide (sequence 15–21) to give the protected peptide methyl ester corresponding to the 15–35 sequence which was then converted to the corresponding hydrazide.

The synthesis of the 25–52 sequence was achieved by assembling the protected peptide hydrazide corresponding to the amino acid residues 25–35, with the C‐terminal heptadecapeptide 36–52. The resulting protected octaeicosapeptide (sequence 25–52) was selectively deblocked with trifluoroacetic acid and acylated with the benzyloxycarbonyldecapeptide hydrazide 15–24 to give the desired octatriacontapeptide corresponding to sequence 15–52 of the inhibitor.

An attempt to prepare the 15–52 sequence through the condensation of fragments corresponding to 15–35 and 36–52 sequences was unsuccessful. The identity and purity of the synthetized peptide derivatives were established by elemental analysis (in some cases), amino acid analysis, optical rotation, and thin‐layer chromatography in two solvent systems. The final products were also evaluated, after partial deprotection with anhydrous hydrogen fluoride or aqueous 90% trifluoroacetic acid, by paper electrophoresis at different pH values.
CHROMOSOMAL PROTEINS
Authors: Walker John M. , Goodwin Graham H. , Johns Ernest W.
Published: August 2010

The amino acid sequence of the first 33 residues of the non‐histone chromosomal protein HMG 14 has been determined. The presence of two regions of common sequence between HMG 14 and both the non‐histone chromosomal protein HMG 17 and the trout specific protein, H 6, is noted.
HUMAN SOMATOTROPIN
Authors: Blake James , Li Choh Hao
Published: August 2010

Three analogs of the carboxyl terminal plasmin fragment of human somatotropin, [Nle170, Ala165,182,189]‐human somatotropin‐(145–191), [Nle170, Ala165,182,189]‐human somatotropin‐(140–191), and [Lys135,136,138, Glu137,139, Nle170, Ala165,182,189]‐human somatotropin‐(135–191) have been synthesized by the solid‐phase method. The synthetic peptides were assayed for growth‐promoting activity and their potency was found to be comparable to that of [S‐carbamideomethylcysteine165,182,189]‐human somatotropin‐(141–191) which was derived from the native hormone.
SYNTHESIS AND CIRCULAR DICHROISM STUDIES OF TWO POLYPEPTIDES H‐[Gly‐(Pro)3]n‐OH and H‐[Gly‐(Pro)4]n‐OH*
Authors: Helbecque N. , Loucheux‐Lefebvre M‐H.
Published: August 2010

Recently Gly‐(Pro)3 a proline‐rich protein (PRP) containing repetitive Gly‐(Pro)3 or Gly‐(Pro)4 sequences was isolated from human parotid saliva. The synthesis of two polypeptides containing these sequences is described. Their circular dichroism spectra have been recorded and are compared with the circular dichroism spectrum of the natural protein.
THE DISSOCIATION OF b‐TSH
Authors: Sorimach Kenji , Condliffe Peter G.
Published: August 2010

In the present study SDS polyacrylamide gel electrophoresis was used to reinvestigate the conditions under which b‐TSH dissociates into its constituent subunits. The effects of SDS itself, urea, acid pH and temperature were assessed by the decrease in the amount of undissociated TSH and the increase in the dissociated components as revealed by SDS gel electrophoresis. In SDS alone 25–30% dissociation occurred. Pre‐treatment with increasing concentrations of urea up to 7.1 M increased the degree of dissociation to 70% after 4 h at room temperature. Maximum dissociation was achieved by treatment at pH 2.5 and 37°C for 1 h. In 1 M propionic acid approximately 10% of the TSH was still undissociated after 18 hat 25° C.
HUMAN TRANSFERRIN, ASIALOTRANSFERRIN AND THE INTERMEDIATE FORMS
Authors: Wong K.‐L. , Debanne M.T. , Hatton M.W.C. , Regoeczi E.
Published: August 2010

Six protein fractions were isolated from mixtures of neuraminidase‐treated and untreated samples of human transferrin type C (TfC) in the 2Fe‐form by chromatography on DEAE‐cellulose. The first 2Fe‐TfC peak (designated TfC‐1–6) to desorb from the column did not contain sialic acid; The second (TfC‐2–6) and third (TfC‐3–6) peaks were intermediates between asialotransferrin and the least acidic component of native 2Fe‐TfC; The fourth, fifth and sixth (TfC‐4–6, ‐5–6 and ‐6‐6) peaks were identical with the three components described earlier for native 2Fe‐TfC. Ratios of N‐acetylneuraminic acid/galactose contents in all peaks were determined by gas‐liquid chromatography of the glycopeptides.

Further heterogeneity in the carbohydrate composition of TfC‐1–6 was demonstrated with the aid of an affinity medium which was obtained by immobilising the asialoglycoprotein‐binding lectin from rabbit liver on Sepharose. This medium separated TfC‐1–6 into a retarded (‘low affinity’) and a retained (‘high affinity’) component, the ratios of which in TfC‐1–6 samples prepared from three individual donors were similar (83–84% and 16–17% respectively). Column chromatography on Sepharose‐concanavalin A (S‐con A) was used to identify the position in the normal DEAE‐chromatogram of those 2Fe‐TfC molecules which, in the desialylated state, give rise to the high‐affinity component in TfC‐1–6. S‐con A divided native 2Fe‐TfC into two components: one that passed through the column with 0.1M NaCl and another which could only be eluted by α‐methyl‐D‐glucoside. After mixing the former component with unfractionated TfC, the electrophoretic band corresponding to TfC‐6‐6 was markedly enriched, and when partially purified TfC‐6‐6 was chromatographed on S‐con A, a large portion of the load failed to specifically bind to the lectin. In contrast, TfC‐5–6 was nearly quantitatively retained by S‐con A. Resolution of TfC‐1–6 on S‐con A was similar to that of native 2Fe‐TfC. From animal studies the protein not retained by S‐con A was identified as high‐affinity TfC‐1–6, whereas the retained portion was of the low‐affinity type. These observations suggest that those 2Fe‐TfC molecules which, after desialylation, show high affinity for the hepatic lectin probably correspond to TfC‐6‐6 in the native state.

Complete desialylation of TfC in a single incubation with neuraminidase appears virtually impossible but homogeneous preparation of TfC‐1–6 can be obtained by chromatography of the incubation mixture on DEAE‐cellulose.
SYNTHESIS AND OPIATE ACTIVITY OF HUMAN β‐ENDORPHIN ANALOGS WITH VARIOUS CHAIN LENGTHS
Authors: Yeung Hin‐Wing , Yamashiro Donald , Chang Wen‐Chang , Li Choh Hao
Published: August 2010

The synthesis of βh‐endorphin* ‐(1–15), ‐(1–21), ‐(1–26), ‐(1–28) and ‐(1–29) have been accomplished by the solid‐phase method. The opiate activities of the peptides were measured in the guinea pig ileum assay. Their relative potencies were βh‐endorphin (βh‐EP), 1.00; Met‐enkephalin, 0.25; βh‐EP‐(1–15), 0.17; βh‐EP‐(1–21), 0.46; βh‐EP‐(1–26), 0.48; βh‐EP‐(1–28), 0.89; βh‐EP‐(1–29), 1.04.
SIDE REACTIONS IN PEPTIDE SYNTHESIS
Authors: Bodanszky Miklos , Kwei Joseph Z.
Published: August 2010

The base catalyzed ring closure in t‐Boc‐Asp‐X β‐naphthylamides was examined in a series of 2‐peptide derivatives in which position X was occupied by the neutral and acidic amino acid residues that occur in proteins. Bulkiness and functional groups in the side chain of X have a major effect on the rate of cyclization, e.g. acidic groups slow down the formation of aminosuccinyl derivatives. Rate‐enhancing effect can be observed in serine and threonine, while the side reaction is unexpectedly slow when X is methionine.
COACERVATION PROPERTIES IN SEQUENTIAL POLYPEPTIDE MODELS OF ELASTIN
Authors: Rapaka Rao S. , Okamoto K. , Urry D.W.
Published: August 2010

Syntheses of two sequential polypeptides H‐(Ala‐Pro‐Gly‐Gly)n‐Val‐OMe and H‐(Ala‐Pro‐Gly‐Val‐Gly)n‐Val‐OMe via the p‐nitrophenyl active ester procedure are reported. The two polymers were obtained in good yields and the polymers were shown to be of large molecular weights, n > 40. These two polypeptides were synthesized as analogs of the two coacervating sequential polypeptides, H‐(Val‐Pro‐Gly‐Gly)n‐Val‐OMe, and H‐(Val‐Pro‐Gly‐Val‐Gly)n‐Val‐OMe, in which the Val‐l residue is replaced by an Ala‐l residue. H‐(Ala‐Pro‐Gly‐Gly)n‐Val‐OMe did not coacervate even at as high a temperature as 100°, and H‐(Ala‐Pro‐Gly‐Val‐Gly)n‐Val‐OMe did not coacervate; however, it precipitated irreversibly around 65–70° C. This suggests the critical role of the Val‐Pro hydrophobic side chain interaction in coacervation.
PHOTOLYTIC INHIBITION AND LABELING OF PROTEINS WITH ARYL DIAZONIUM COMPOUNDS
Authors: Tometsko Andrew M. , Turula Jon , Comstock Jeanne
Published: August 2010

In the course of preparing aryl azide derivatives for use as photoprobes, we have observed significant light sensitivity in the precursor aryl diazonium compounds. The photosensitive properties of this class of compounds are of interest since they will seek out cationic binding sites in biological targets, and can be employed to inhibit complementary targets at acid pH. The relationship between photolytic change in the structure of diazonium compounds and the corresponding change in function of a biological target are presented. Experiments are described in which the dark and light sensitive properties of a model diazonium compound, diazobenzene sulfonate (DBS), were determined. The ultraviolet spectra were used to evaluate the dark stability and light sensitivity of DBS. Chymotrypsin and trypsin served as functioning targets for further evaluation of the photochemical properties. Both enzymes are stable to the probe in the dark at acid pH. A rapid loss of enzyme activity was observed following flash photolysis of DBS‐enzyme solutions. Photolytic incorporation of radioactive DBS into chymotrypsin was observed. Aryl diazonium salts can be employed to probe the availability of complementary sites in biological targets at different acid pH values.
THE DENATURATION OF COVALENTLY INHIBITED SWINE PEPSIN
Authors: Ahmad Faizan , Mcphie Peter
Published: August 2010

Studies are reported on the denaturation of freshly prepared, intact swine pepsin, which was inactivated by reaction with diazoacetylglycine ethyl ester, to prevent autolysis. Denaturation about pH 6 was found to involve a small expansion of the molecular domain with some loss of organized secondary structure. On the other hand, increasing concentrations of guanidine hydrochloride induced cooperative transitions in both the native and alkali denatured forms to give a cross‐linked random coil. No conditions could be found in which these reactions were reversible. Removal of denaturing conditions usually resulted in aggregation and precipitation of protein. From these studies, it would seem that the active conformation is largely predetermined in the zymogen.
CIRCULAR DICHROISM SPECTRA OF ISOLATED SOYBEAN AND CHICKPEA TRYPSIN‐CHYMOTRYPSIN INHIBITORS
Authors: Bewley Thomas A. , Birk Yehudith
Published: August 2010

Circular dichroism spectra of trypsin‐chymotrypsin inhibitors from soybeans and chickpeas have been determined in acidic, neutral and highly alkaline solutions. Neither protein contains α‐helix although a small amount ofβ‐structure cannot be excluded. Negative dichroism above 250 nm has been assigned largely to disulfide bonds in both molecules with neither showing evidence for tyrosine residues buried in hydrophobic regions. The spectra of these inhibitors between 230 and 250 nm have been compared with the spectra of a number of structurally related proteins suggesting that previous interpretations of this region may have been incomplete or incorrect.
ISOLATION AND PARTIAL SEQUENCE OF THE CYANOGEN BROMIDE PEPTIDES FROM CALF THYMUS NON‐HISTONE CHROMOSOMAL PROTEIN HMG 1
Authors: Walker John M. , Parker Bridget M. , Johns Ernest W.
Published: August 2010

Peptides produced by cyanogen bromide cleavage of non‐histone chromosomal protein HMG 1 have been isolated and characterized, and their partial sequences determined. The sequence data presented here account for over half of the sequence of the HMG 1 molecule and, together with previously published results, provide interesting information on the charge distribution within the molecule.
SIDE REACTIONS IN PEPTIDE SYNTHESIS
Authors: Martinez Jean , Bodanszky Miklos
Published: August 2010

The base‐catalyzed ring closure ofβ‐benzylaspartyl peptides was efficiently suppressed by the addition of phenols (with electron‐withdrawing substituents) to the reaction mixtures. From a series of compounds tested, 2,4‐dinitrophenol and pentachlorophenol were the most effective. No direct relationship was found between the acidity of the additives and their ability to suppress the formation of aminosuccinyl peptides. The applicability of 2,4‐dinitrophenol and pentachlorophenol in practical syntheses was also examined.
PURIFICATION AND CHARACTERIZATION OF AN ACID PROTEASE FROM MONASCUS KAOLIANG*
Authors: TSAI M. S. , Hseu T. H. , Shen Y. S.
Published: August 2010

An acid protease from Monascus kaoliang was purified by consecutive applications of fractional acetone precipitation, batchwise CM‐cellulose method and DEAE‐cellulose column chromatography. The preparation was homogeneous on disc polyacrylamide gel electrophoresis at pH4.5 and 7.5. The yield was about 30% with overall increase in specific activity of about 6‐fold. The molecular weight as determined by SDS gel electrophoresis was about 34,000. The enzyme was a glycoprotease as indicated by specific carbohydrate staining on gels. It possessed the nature of an acid protease with a pH optimum at 3.0 toward heat‐denatured casein and was stable over the range of pH 3.0 to 6.0. Reducing agents and thiol poisons had no effect on this enzyme, suggesting that free sulfhydryl groups were not required for enzyme activity. Diisopropyl fluorophosphate did not inactivate this protease, indicating the probable absence of serine residue in the active site. The enzyme was inactivated by reaction with the carboxy‐group specific reagent, 1,2‐epoxy‐3‐(p‐nitrophenoxy) propane (EPNP). Pepstatin, a specific inhibitor for pepsin, was shown to inhibit this enzyme strongly. However, biacetyl (2,3‐butadione) had little effect on this protease, although it inactivated pepsin to an 85% activity loss. Also, p‐bromophenacyl bromide, another specific inhibitor of pepsin, failed to inactivate this acid protease.
ISOLATION OF ANTITUMOR PROTEINS ABRIN‐A AND ABRIN‐B FROM ABRUS PRECATORIUS*
Authors: Lin Jung‐Yaw , Lee Te‐Chang , Tung Ta‐Cheng
Published: August 2010

Two toxic proteins were purified from the seeds of Abrus precatorius by DEAE‐A 50 and Sepharose 4B chromatography. One of them does not bind on the Sepharose 4B column (Abrin‐b) and the other (Abrin‐a) is eluted with 0.2 M galactose. The amino acid compositions and tryptic maps of these two proteins were similar, but not identical. The molecular weights estimated by SDS‐gel electrophoresis were 67,000 for abrin‐b as compared with 65,000 for abrin‐a. In the presence of mercaptoethanol, both abrin‐a and abrin‐b gave rise to two bands.

The lethal doses of abrin‐a and abrin‐b for mice recorded within 48 h were 10 and 25μg per kg of body weight respectively. Abrin‐a at 0.8 μg per ml concentration level agglutinated human 0‐type erythrocytes, whereas abrin‐b showed no such activity. Abrin‐a at 5 μg per ml concentration level agglutinated both the Sarcoma 180 cells and Ehrlich ascites tumor cells, but it required 150 μg per ml for abrin‐b. Both these two proteins at a sublethal dose could inhibit the growth of Ehrlich ascites tumor cells which were injected simultaneously with these proteins.

131I‐abrin‐a and 131I‐abrin‐b were able to bind Sarcoma 180 cells, and the binding of abrin‐a could be inhibited by lactose, raffinose, galactose and rhamnose, but none of 15 sugars tested inhibited the binding of abrin‐b.
ISOLATION AND PRIMARY STRUCTURE OF ADRENOCORTICOTROPIN FROM SEVERAL SPECIES OF WHALE
Authors: Kawauchi Hiroshi , Muramoto Koji , Ramachandran J.
Published: August 2010

The isolation of adrenocorticotropin (ACTH) from fin (Balaenoptera physalus), sei (Blaenoptera borelis) and sperm (Physeter catodon) whale pituitaries is described.

Their primary structures have been elucidated by the fluorescein isothiocyanate method and revealed to be identical to the structure of the human hormone. Fin whale exhibited an identical steroidogenic activity to that of the porcine hormone.
A LIPOPHILIC DERIVATIVE OF NEOCARZINOSTATIN A Polymer Conjugation of an Antitumor Protein Antibiotic*
Authors: MAEDA H. , TAKESHITA J. , KANAMARU R.
Published: August 2010

A lipophilic derivative of neocarzinostatin (NCS), an antitumor antibiotic, was prepared by reaction with a synthetic water‐soluble polymer, [(styrene)1˜3‐(maleic acid4˜7/anhydride1)]. The reaction was carried out at pH 8.6 for 3 h and aimed at modifying the two nonessential aming (of Ala‐1, ε‐amino of Lys‐20). The NCS‐polystyrene (SMANCS was a column of Sephadex G‐100 in 0.05 M ammonium bic and the main product was obtained as a single peak. The elemental and showed an increased C and a decreased N content. U.v. and i.r. absorption ectra for SMANCS showed the presence of styrene. SDS‐acrylamide gel electrophoresis at pH 8.5 and the decreased N content suggested a molecular high of about 25 000, Indicating the numbers of polymers conjugated to be six units, two of which were found attached to the two amino groups. SMANCS was solution in organic solvents, in contrast to NCS, and in water. SMANCS increased chemical and biological stability and appeared molicular in vitro biological activity.
TRINITROPHENYLATION OF BOVINE GROWTH HORMONE
Authors: BONINO M.J. BISCOGLIO DE JIMENEZ , CASCONE O. , SANTOMÉ J.A.
Published: August 2010

Bovine growth hormone was chemically modified with picryl sulfonic acid, at pH 8.4 during 2 and 5 min of reaction. The N‐terminal residue provides the most reactive amino group followed by the amino groups of lysine 179 and lysines 143, 69, 111, 170 and 166 in decreasing order.

These results agree with those obtained previously with equine growth hormone, except that residue 156 is not modified in bovine growth hormone, An important decrease in biological activity occurs between 2 and 5 min of reaction without sensible modification in the α‐helix content of the molecule.
SECONDARY STRUCTURE PREDICTION OF ANTERIOR PITUITARY HORMONES Lack of Correlation between Predicted Values and Circular Dichroism Data
Authors: JIBSON MICHAEL D. , LI CHOH HAO
Published: August 2010

The secondary structures of human somatotropin, human choriomammotropin, ovine and porcine prolactin, human, ovine and porcine β‐lipotropin, human and ovine lutropin, human thyrotropin, human corticotropin, α‐melanotropin and human β‐melanotropin have been predicted by the method of Chou & Fasman. Predicted contents of α‐helix and β‐sheet do not correspond well with values estimated from circular dichroism spectra.
FURTHER CHARACTERIZATION OF THE OVINE LUTROPIN α AND β SUBUNITS PREPARED BY THE SALT PRECIPITATION METHOD
Authors: SAIRAM M. R.
Published: August 2010

The subunits of ovine lutropin prepared by acid dissociation and salt precipitation were characterized by end group analysis, tryptic peptide mapping, SDS gel electrophoresis and biological activity. No evidence of internal peptide cleavage was found in the α subunit. The subunits possessed low activity. The α and β subunits recombined effectively to generate a complex that had full receptor binding activity and in vitro biological activity. The recombinants of subunits prepared by countercurrent distribution showed only 50% activity in both assays. The salt precipitation method α subunit could be completely reduced and reoxidized in the absence of denaturants. The reoxidized α subunit combines with the native β subunit generating full activity. However, this recombined hormone tends to lose activity with time, suggesting that the reoxidation may not fully restore the native structure of the reduced α subunit. The native lutropin α subunit effectively combined with follitropin β subunit generating complete follitropin activity.
ELECTRON MICROSCOPE STUDY ON HUMAN CERULOPLASMIN
Authors: SAMSONIDZE T. G. , MOSHKOV K. A. , KISELEV N. A. , NEIFAKH S. A.
Published: August 2010

Electron microscopy of human ceruloplasmin (CP) molecules revealed a few distinctive types of particle images. Analysis of these images allows to propose a tentative model for CP: six “subunits” (which we call domains) not much different in size are arranged with 32 point group pseudosymmetry. The determination of the number of polypeptides arising at the spontaneous specific proteolytic fragmentation of CP and their molecular weights conform with this assumption. The electrophoretic studies of the CP samples preparated both with and without potent proteolytic inhibitor, PMSF, revealed that CP is a single‐chain protein with molecular weight of 130000. Isolated and stored without PMSF the polypeptide chain of CP undergoes specific proteolytic cleavage which results in the appearance of polypeptides with molecular weights of 16 000, 48 000, and 64 000. The latter two polypeptides degradate to about two‐ and three‐fold decreased molecular weights fragments, respectively. Therefore, the single polypeptide chain of CP contains at least five peptide bonds which are particularly susceptible to proteolytic attack and which connect six principal segments of the chain. The hydrolysis of these bonds results in liberation of the six fragments which were integrated in the enzymatically active globule of CP.