bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS FROM COMBINING UREA AND AN ALCOHOL ON THE HEAT‐INDUCED REVERSIBLE DENATURATION OF RIBONUCLEASE
Authors: Gerlsma Sicco Y. , Stuur Elzo R.
Published: August 2010

The effects of a combination of an alcohol and urea on the transition temperature of bovine ribonuclease were investigated. The combined effects on the transition temperature of ribonuclease of a polyvalent alcohol and urea are about equal to the algebraic sum of the effects of each individual additive. The effects of a monovalent alcohol and urea are not cumulative, especially not at low temperatures (30°C). The presence of urea decreases the hydrophobic effect of a monovalent alcohol, strongly at low temperatures, to a lesser degree at high temperatures (60°C). Consequently, urea hinders the interhydrophobic interactions by affecting the water molecules.
STUDIES ON TRYPSIN INHIBITORS
Authors: Guggi Augusto , Tomatis Roberto , Benassi Carlo A. , Rocchi Raniero
Published: August 2010

Synthesis is described of the protected undecapeptide tert‐butyloxycarbonylisoleucyl‐threonyltyrosylserylasparaginyl‐γ‐ tert‐butylglutamyl‐S‐acetamidomethylcysteinyl‐valylleucyl‐S‐acetamidomethylcysteinylserine hydrazide corresponding to positions 25–35 of the amino acid sequence of porcine pancreatic secretory trypsin inhibitor II (Kazal).

The heptapeptide free base methyl asparaginyl‐γ‐tert‐butylglutamyl‐S‐aceta‐midomethylcysteinylvalylleucyl‐S‐acetamidomethylcysteinylserinate (sequence 29–35) was acylated, by the azide procedure, with the tetrapeptide tert‐butyloxycarbonyl‐isoleucylthreonyltyrosylserine hydrazide (sequence 25–28) and the resulting tert‐butyloxycarbonylundecapeptide methyl ester was transformed into the corresponding hydrazide by hydrazinolysis.

The stereochemical homogeneity of the final product was assessed, after partial deprotection with aqueous 90% trifluoroacetic acid, by digestion with papain and aminopeptidase M followed by quantitative amino acid analysis.
STUDIES ON TRYPSIN INHIBITORS
Authors: Tomatis Roberto , Guggi Augusto , Menegatti Enea , Rocchi Raniero
Published: August 2010

Synthesis is described of the partially protected octapeptide tert‐butyloxycarbonyl‐γ‐tert‐butylglutamylasparaginyl‐Nε‐trifluoroacetyllysyl‐Nε‐trifluoroacetyllysylarginyl‐Nγ‐4,4'‐dimethoxybenzhydrylglutaminylthreonylproline corresponding to positions 36–43 of the amino acid sequence of porcine pancreatic secretory trypsin inhibitor II. The tetrapeptide free base arginyl‐Nγ‐4,4′‐dimethoxybenzhydrylglutaminylthreonyl‐proline was acylated, by the azide procedure, with the tripeptide benzyloxycarbonyl‐asparaginyl‐Nε‐trifluoroacetyllysyl‐Nε‐trifluoroacetyllysine hydrazide. The resulting protected heptapeptide was partially deblocked by catalytic hydrogenation and reacted with α‐1‐succinimidyl‐γ‐tert‐butyl tert‐butyloxycarbonylglutamate. The stereochemical homogeneity of the ensuing octapeptide was assessed, after partial deprotection with aqueous 90% trifluoroacetic acid, by digestion with papain and aminopeptidase M followed by quantitative amino acid analysis.
THERMODYNAMIC PARAMETERS OF TRANSFER OF N‐ACETYL ETHYL ESTERS OF DIFFERENT AMINO ACIDS FROM ORGANIC SOLVENTS TO WATER
Authors: Nandi Pradip K.
Published: August 2010

The distribution coefficients of N‐acetyl ethyl esters of glycine, diglycine, β‐alanine, alanine, valine, norvaline, leucine and norleucine between water and different organic solvents have been measured at different temperatures. Similar distribution coefficients have been measured for simple amides, urea, formamide, acetamide and N‐methyl acetamide. From the distribution measurements, ΔGtr, the free energy of transfer of the solutes from organic solvents to water has been calculated. The temperature dependence of the distribution coefficient values has been utilised to determine the enthalpy of transfer, ΔHtr, and entropy of transfer ΔStr for the above process. From these results similar thermodynamic parameters for the transfer of different nonpolar side chains and peptide groups have been determined and compared with the available data in the literature.
STUDIES ON MOLECULAR STRUCTURE, SYMMETRY AND CONFORMATION. XV.
Authors: Swaminathan P. , Srinivasan R.
Published: August 2010

The common features in the crystal and molecular structures of stereo‐isomers of threonine are discussed from the data available on seven compounds. Weighted mean values of the bond lengths and angles of threonine are given. Conformational and configurational features are also compared.
N‐ACETYLSERINE IN HORSE MUSCLE ACYL‐PHOSPHATASE
Authors: Cappugi G. , Chellini P. C. , Nassi P. , Ramponi G.
Published: August 2010

A ninhydrin‐negative peptide fraction obtained from tryptic digest of carboxymethyl acylphosphatase was isolated by chromatography on a column of PA 28 Beckman resin and analysed for the amino acid composition. Degradation with carboxypeptidase B and A indicated that the sequence of this peptide was: X‐Thr‐Ala‐Arg. The amino‐terminal residue was identified as N‐acetylserine by high voltage electrophoresis. It is therefore suggested that the sequence of the NH2‐terminal portion of CM‐acylphosphatase is N‐acetyl‐Ser‐Thr‐Ala‐Arg. Digestion with carboxypeptidase A and B indicated also that the COOH‐terminal portion of CM‐acylphosphatase is ‐Arg‐Tyr‐OH.
CLEAVAGE OF HUMAN SERUM TRANSFERRIN WITH N‐BROMOSUCCINIMIDE*
Authors: Bezkorovainy Anatoly , Grohlich Dietmar , Sly Dayle A.
Published: August 2010

Human serum transferrin was fragmented by N‐bromosuccinimide and reduction‐alkylation. It was observed that there were at least two each of tryptophanyl‐serine and tryptophanyl‐aspartic acid, and one each of tryptophanyl‐alanine and trypto‐phanyl‐glutamic acid bonds. The size of fragments detected by polyacrylamide gel electrophoresis ranged from 8,000 to 70,000 daltons. Several of the fragments were isolated in a homogeneous form with respect to molecular weight, but were shown to be mixtures of at least five molecular species each by end group analysis.
PRIMARY STRUCTURE OF EQUINE GROWTH HORMONE
Authors: Zakin M. M. , Poskus E. , Langton A. A. , Ferrara P. , Santomé J. A. , Dellacha J. M. , Paladini A. C.
Published: August 2010

The study of the structure of the peptides arising from native, oxidized, reduced and alkylated or citraconylated equine growth hormone on incubation with trypsin and chymotrypsin is reported.

The data obtained, combined with results already published, support the assembly of a unique sequence of amino acids for the polypeptide chain of the protein.
CONFORMATIONAL ANALYSIS OF A CHAIN REVERSAL IN α‐CHYMOTRYPSIN
Authors: Hurwitz F. I. , Hopfinger A. J.
Published: August 2010

A complete conformational analysis of the fold (Asp‐Lys‐Thr‐Gly) (residues 35–38), and additional adjacent residues of α‐chymotrypsin has been performed. A comparison of these findings with those of Lewis et al. (1) is made, and a discussion of the implications of protein‐fold models is discussed. This particular residue sequence prefers to bend over maintaining a helical conformation. However, the bend conformation of the tetramer is different from that of the native bend. The native bend conformation is nearly realized when an additional residue of the native primary structure is added to each side of the tetramer. Early and late folding‐sequence studies suggests that while the native fold is of low energy, there are fold‐points along the primary structure which are more stable. The structural implications of this finding are discussed.
STUDIES ON A PROTAMINE (GALLINE) FROM FOWL SPERM.
Authors: Nakano Minoru , Tobita Tohru , Ando Toshio
Published: August 2010

Of the eight fractions (G‐I‐G‐VIII) obtained from galline, a protamine from rooster sperm nuclei, the complete amino acid sequences of two fractions G‐I and G‐V have already been reported. Other fractions of galline purified repeatedly on the column of Bio‐Gel CM‐30 were submitted to structural analyses. The complete amino acid sequences of three (G‐II, G‐III and G‐VII) of the fractions and the partial chemical structures of two (G‐VI and G‐VIII) of the fractions were established from the results of analyses of the tryptic and chymotryptic peptides together with those of end groups and terminal sequences. Remarkable similarities have so far been found in the sequences of these fractions. Combining these results with those complementarily explained in the following paper, it was finally confirmed that the intact galline molecule is composed of only one molecular species (G‐VIII) and that fractions (G‐I‐G‐VII) were derived from G‐VIII by the action of an inherent protease in the preparation process. Consequently, the total amino acid sequence of the intact galline is concluded to be as follows: H‐Ala‐Arg‐Tyr‐Arg‐Ser‐Arg‐Gly‐Arg‐Ser‐Arg‐Ser‐Arg‐Arg‐Thr‐Arg‐Arg‐Arg‐Arg‐Ser‐Pro‐Arg‐Ser‐Gly‐Arg‐Arg‐Arg‐Ser‐Pro‐Arg‐Arg‐Arg‐Arg‐Ser‐Arg‐Arg‐Arg‐Arg‐Arg‐Tyr‐Gly‐Ser‐Ala‐Arg‐Arg‐Ser‐Arg‐Arg‐Ser‐Gly‐Gly‐Val‐Arg‐Arg‐Arg‐Arg‐Tyr‐Gly‐Ser‐Arg‐Arg‐Arg‐Arg‐Arg‐Arg‐65Tyr‐OH.
SEPARATION OF THE TWO DOUBLE‐CHAIN BOVINE INTERMEDIATES OF THE PROINSULIN‐INSULIN CONVERSION I. CHEMICAL, IMMUNOCHEMICAL, CIRCULAR DICHROISM, AND BIOLOGICAL CHARACTERIZATION
Authors: Markussen Jan , Heding Lise G.
Published: August 2010

The intermediates of the proinsulin‐insulin conversion were separated by cation exchange. The circular dichroism spectra of the intermediates showed less α‐helix than insulin and proinsulin. It is suggested that the C‐peptide interacts with the section of α‐helix contained between residues 2 and 8 in the A‐chain of the insulin moieties and unwinds the α‐helix. The in vivo activities of the intermediates were found to be in the order of 50% relative to insulin. In the fat cell assay, the A‐chain‐substituted form is weaker (9%) than the B‐chain‐substituted form (19%). The C‐peptide segments of the two forms reacted with C‐peptide‐specific antibodies as fully as the free C‐peptide, on a molar basis. In contrast, the insulin segments were hindered from reacting with insulin‐specific antibodies as fully as the insulin.
MODIFICATION OF LIPOXYGENASE BY HYDROGEN PEROXIDE AND PHOTOOXIDATION
Authors: Aoshima Hitoshi , Kajiwara Tadahiko , Hatanaka Akikazu , Nakatani Hiroshi , Hiromi Keitaro
Published: August 2010

The kinetic study of fluorescence stopped‐flow method suggested that the interaction between lipoxygenase and H2O2 is consistent with a simple irreversible one‐step mechanism. The activation energy of the reaction was 7.2 kcal/mol. Participation of an ionizable group with pK about 8.8, possibly a histidine residue, was suggested from the pH‐dependence of the rate constant. No further fluorescence quenching of lipoxygenase was observed when the product was added to the lipoxygenase solution before mixing the lipoxygenase and H2O2 solutions. The fluorescence quenching of lipoxygenase by H2O2 was in parallel with the inactivation of the enzyme. Hydroperoxylinoleic acid strongly protects the inactivation of lipoxygenase caused by H2O2. These results are consistent with an interpretation that OH and/or O‐ are produced when the iron of the enzyme is oxidized by H2O2, which in turn will attack some amino acid essential for the enzyme activity. The pH‐dependence of the inactivation rate constant of photooxidation of lipoxygenase sensitized by methylene blue indicated that an ionizable group with pK about 8.8 is concerned with the enzymatic activity. In contrast to the inactivation of lipoxygenase by H2O2, the product protected the inactivation of the enzyme by photooxidation only at high concentration.
REGULAR REPEATS IN THE SEQUENCE OF TROPOMYOSIN
Authors: Longley W.
Published: August 2010

The sequence of tropomyosin contains 13 out of the 14 residues necessary to form a set of seven pairs of charged groups repeating at intervals of 57 å. These pairs could be involved in the interaction of tropomyosin with actin.
THE MOLECULAR COMPONENTS OF HUMAN TRANSFERRIN TYPE C
Authors: Regoeczi E. , Wong K.‐L. , Ali M. , Hatton M.W.C.
Published: August 2010

Immunologically pure human transferrin type C (TfC) was isolated from the plasmas of 11 individual healthy donors. After conversion into the 2Fe‐form, the preparations were analysed by polyacrylamide gel electrophoresis and chromatography on DEAE‐cellulose. In all samples studied by either method the presence of three components, designated A, B and C, was observed. Calculations from eight chromatograms yielded the following relative proportions for the components: A:6%, B:62% and C:32%. The quantity of iron bound played no role in this chromatographic resolution. The components were immunologically identical but their sialic acid content increased in the order of A<B<C. The presence of galactose as an ultimate residue of the oligosaccharide chains in TfC component A was confirmed by a biological test. This observation, together with the results of earlier analyses for hexose, hexosamine and galactose in the subfractions from Behringwerke human transferrin, suggests that sialic acid is probably the only variable among TfC components A, B and C. Loss of sialic acid from component C during the isolation of TfC was excluded as an explanation for the presence of the other two components. The electrophoretic appearance of TfC samples from five patients with liver disease (chronic active hepatitis, cirrhosis or alcoholic liver) did not noticeably differ from that of TfC from healthy persons. Baboon transferrin resembles TfC with respect to sialic acid heterogeneity. This species was therefore studied to decide whether sialic acid is gradually lost from transferrin in the circulation or whether transferrin is not fully sialylated before discharge from the hepatocyte. Using DEAE‐cellulose chromatography no difference was found between baboon transferrin molecules which were less than 6h old and those which had a mean age of 8.9 days. By inference it is suggested that the reason for the multiplicity of TfC is also likely to be biosynthetic.
THEORETICAL STUDIES ON β‐LACTAM ANTIBIOTICS:
Authors: Virudachalam R. , Rao V.S.R.
Published: August 2010

The substrate analogue hypothesis proposed for the mechanism of the action of penicillins and cephalosporins is examined by stereochemical criteria. Theseβ‐lactam antibiotics assume conformation similar to X‐D‐alanyl‐D‐alanine due to the presence of the lactam ring; this disagrees with the assumption made by Tipper & Strominger that L and D amino acid residues take similar conformation. The model proposed in this study for the activity of these antibiotics differs considerably from the earlier models, mainly in φ2 rotational angle which determines the conformation of the aminoacyl group. The inactivity of C6 or C7 epimers and the effect of various substitutions at 6α or 7α and C2 positions of penicillins and cephalosporins on the biological activity are explained.
EXPLANATION OF THE OBSERVATION OF PANCREATIC RIBONUCLEASE ACTIVITY AT pH 4.5
Authors: Bartholeyns Jacques , Wang Dalton , Blackburn Peter , Wilson Glynn , Moore Stanford , Stein William H.
Published: August 2010

A recent conclusion that beef pancreas contained a molecular species of ribonuclease with intrinsically high activity at pH 4.5 has been found to be incorrect. The particular assay used in the earlier experiments gives anomalous results at acid pH in the presence of low concentrations of ions such as phosphate which was used during the fractionation. By turning to the more widely employed form of the perchloric acid precipitation assay, interference is avoided and the ribonuclease in beef pancreas is confirmed as consisting almost completely of the molecular species well‐characterized as ribonuclease A. The clarification of the assay question permits a clear interpretation of the results of each step of the chromatographic purification procedure that led to the initial conclusion, including an artifact that arose when gel filtration was attempted with distilled water rather than with buffer.
THE SECONDARY STRUCTURE OF HISTONE IV AND ITS STABILITY
Authors: Pekary A. Eugene , Chan Sunney I.
Published: August 2010

The secondary structure within histone IV and its fragments obtained by cyanogen bromide (CNBr) cleavage at Met 84 has been examined by circular dichroism and spectrophotometric pH titration measurements. These studies have confirmed the existence of stable secondary structure within the C‐terminal fragment of histone IV (C‐peptide) which can be perturbed only by 6 M urea at pH > 8 or 8M guanidine ˙ HCl. In contrast, the N‐terminal fragment (N‐peptide) appears to lack significant secondary structure at low ionic strengths but acquires approximately 15%β‐sheet conformation and 5%α‐helix upon aggregation at ionic strengths ≥ 0.4.

The rates of nitration of the N‐ and C‐peptides by tetranitromethane (TNM) have also been measured as a function of ionic strengths. Under comparable conditions, the rate constant for nitration of the N‐peptide was found to be about six times greater than that for the C‐peptide, further evidence in support of the presence of stable secondary structure within the C‐terminal region of histone IV. After binding these histone IV fragments to DNA, however, the nitration reaction rate constants for the N‐ and C‐peptide in the bound form are found to be 2% and 27% of the corresponding free peptides. Reconstituted nucleohistone IV is about 10% as reactive to TNM as histone IV at comparable ionic strength.
SYMMETRICAL FEATURES IN POLYPEPTIDE HORMONE‐RECEPTOR INTERACTIONS
Authors: Beddell Dr.C.R. , Sheppey G.C. , Blundell T.L. , Sasaki K. , Dockerill S. , Goodford P.J.
Published: August 2010

Symmetrical features were observed in the amino acid sequences of some biologically active peptides. It is suggested that this approximate symmetry is reflected in the conformations of the peptides at their respective biological receptors, and has arisen by natural selection as both peptides and receptors evolved to optimise their mutual fit. It follows that the binding site for each peptide at its receptor would share the same symmetry element. This would arise if the peptide binds to two symmetrically related similar or identical submits in the receptor.
pH CONTROLLED DIAZO COUPLING OF ALDOLASE
Authors: MontagnolI Giorgio , Balestreri Ettore , Nannicini Luciano , Bellucci Alberto , Bracaloni Maura
Published: August 2010

pH Conditions have been found which achieve selective reaction of diazotized p‐amino benzoate with cysteine residues of rabbit muscle aldolase. The difference in reactivity of the two sulphydryl groups involved, (Cys—237 and Cys—287) permits one to form either four or eight diazothioethers on the tetrameric enzyme and obtain a homogeneous protein. In both cases the enzyme became slightly more active in the fructose‐1, 6‐bisphosphate cleavage, the KM value being retained. The results have been discussed with regard to chemically modifying an enzyme to change its physical, chemical and immunological properties, whilst leaving the catalytical activity unmodified.
SIZE AND SHAPE OF TWO INTESTINAL DIPEPTIDASES
Authors: Sjöström Hans , NoréN Ove
Published: August 2010

Physicochemical parameters were determined on glycyl‐L‐leucine hydrolase (glycyl‐leucine dipeptidase, EC 3.4.13.2) and aminoacyl‐L‐proline hydrolase (proline dipeptidase, EC 3.4.13.9), purified from pig small intestine. The native molecular weights were found to be 115,000 and 113,000, respectively, as determined by a sedimentation equilibrium technique. Under denaturing conditions the molecular weights were found to be 51,000 and 63,200, respectivemy, using the same technique. It is concluded that each dipeptidase is composed of two subunits of equal molecular weight.

The two dipeptidases have the same Stokes radius, 4.2 nm, analysed by gel chromatography. The sedimentation coefficients were found to be 5.8 S and 6.5 S and the intrinsic viscosities 5.4 ml/g and 5.8 ml/g, respectively. For both dipeptidases the measured physicochemical parameters are in accordance with the model of a prolate ellipsoid of revolution, having an axial ratio of about 5.
SYNTHESIS AND BIOLOGICAL ACTIVITY OF OVINE β‐LIPOTROPIN‐(41–91)‐HENKAIPENTEKONTAPEPTIDE
Authors: Lemaire Simon , Yamashiro Donald , Li Choh Hao
Published: August 2010

The 51‐residue peptide ovine β‐lipotropin‐(41–91) has been synthesized by the solid‐phase method in about 5% overall yield. The synthetic product was characterized by partition chromatography on agarose gel, thin‐layer chromatography in two solvent systems, paper electrophoresis at two pH values, polyacrylamide gel electrophoresis, amino acid analyses of acid and enzymic hydrolysates, and bioassay for lipolytic and melanotropic activities. The synthetic peptide is about 5.4 times as active on a weight basis as ovine β‐lipotropin in the lipolytic assay. In the melanotropic assay, it was about 2.4 times more active than the β‐lipotropin but only 5% as active as bovine β‐melanotropin. It had negligible opiate activity in the guinea pig ileum assay.
[52‐HOMOSERINE] ‐BASIC PANCREATIC TRYPSIN INHIBITOR
Authors: Dyckes D. F. , Creighton T. E. , Sheppard R. C.
Published: August 2010

Treatment of basic pancreatic trypsin inhibitor (BPTI) with cyanogen bromide smoothly cleaves the polypeptide chain at the single methionyl residue. The newly formed homoserine lactone and α‐amino functions are held in proximity by a disulfide linkage, and in neutral aqueous solution react together spontaneously to re‐form the peptide chain. The resulting analog, [52‐homoserine]‐BPTI is very similar to the native molecule in most properties measured. The rate of formation of this analog from the chain‐cleaved intermediate has been determined. It is apparent that the facility of analog synthesis is due in large part to the retention of the native protein conformation in the cyanogen bromide‐cleaved intermediate.
PREPARATION OF PROTECTED PEPTIDE HYDRAZIDES FROM THE ACIDS AND HYDRAZINE BY DICYCLOHEXYLCARBODIIMIDE‐HYDROXYBENZOTRIAZOLE COUPLING
Authors: Wang S. S. , Kulesha I. D. , Winter D. P. , Makofske R. , Kutny R. , Meienhofer J.
Published: August 2010

A mild procedure for preparing protected peptide hydrazides directly from the corresponding carboxylic acids and equivalent amounts of hydrazine, N‐hydroxybenzotriazole and dicyclohexylcarbodiimide is described. Side reactions frequently encountered in hydrazinolysis are thus totally avoided. The process is especially useful for the preparation of aspartic acid and glutamic acid containing peptide hydrazides. No racemization of the amino acid residue was observed.
REACTION OF OVINE PROLACTIN WITH 2‐(2‐NITROPHENYLSULFENYL)‐3‐METHYL‐3‘‐BROMOINDOLEMINE*
Authors: Houghten Richard A. , Li Choh Hao
Published: August 2010

The two tryptophan bonds at positions 91 and 150 in ovine prolactin have been cleaved by the use of 2‐(2‐nitrophenylsulfenyl)‐3‐methyl‐3′‐bromoindolemine. The reaction yielded three products: a small fragment containing residues 92–150, a large fragment consisting of residues 1–91 and 151–199 joined by a disulfide bond, and a derivative containing uncleaved but oxidized prolactin. The yield of the two fragments was 38% and 26%, respectively, indicating a cleavage of approximately 55% for each tryptophan residue. The products were characterized by exclusion chromotography, amino acid analysis, isoelectric focusing on polyacrylamide, circular dichroism spectra, two‐dimensional chromatography/electrophoresis on tryptic digests, and ultraviolet absorption spectra. The oxidized but uncleaved product had immunological activity, whereas the two fragments had none. None of these derivatives was active as assayed by the pigeon crop‐sac test.
INHIBITION OF THROMBIN AND TRYPSIN BY TRIPEPTIDE ALDEHYDES
Authors: Bajusz S. , Barabas E. , Tolnay P. , Szell E. , Bagdy D.
Published: August 2010

Inhibitory effects of certain tripeptide aldehydes on both thrombin and trypsin have been found to be strongly substrate‐dependent. These compounds should therefore be considered as inhibitors of the particular proteolytic reaction for which they had been designed rather than real enzyme inhibitors, i.e. protein or polypeptide proteinase inhibitors of natural origin.
REMOVAL OF t‐BUTYL AND t‐BUTOXYCARBONYL PROTECTING GROUPS WITH TRIFLUOROACETIC ACID
Authors: Lundt Behrend F. , Johansen Nils L. , Vølund Aage , Markussen Jan
Published: August 2010

The trifluoroacetic acid‐mediated removal of t‐butyl groups in protected amino acids leads to the formation of t‐butyl trifluoroacetate. This t‐butyl ester alkylates in trifluoroacetic acid methionine and tryptophan. The t‐butyl trifluoroacetate ester can be destroyed by scavengers commonly employed for t‐butyl cations, and the reaction rates of the scavengers with the ester are used in the evaluation of scavengers. Scavengers of sulphide structure react with t‐butyl trifluoroacetate to form sulphonium compounds, which possess alkylating properties.

In the presence of a scavenger during acidolysis, the trifluoroacetic acid and the scavenger will compete in reacting with the t‐butyl cations. Kinetic studies show comparable reaction rates with thiophenol as scavenger. The usefulness of adding scavengers to trifluoroacetic acid in deblocking reactions is due to the removal of t‐butyl trifluoroacetate in addition to the removal of t‐butyl cations.

Isobutene reacts with trifluoroacetic acid and yields t‐butyl trifluoroacetate. The reaction reaches an equilibrium displaced in favour of the ester at room temperature. Hence no isobutene can be expected to escape during a deblocking reaction in trifluoroacetic acid.
PURIFICATION AND PROPERTIES OF NON‐PRECIPITATING ANTIBODIES TO COBROTOXIN*
Authors: Yang C.C. , Chang C.C. , Lin M.F. , Lee H.Y. , Chuang L.Y.
Published: August 2010

The heterogeneity of precipitating and non‐precipitating antibodies to cobrotoxin was demonstrated by their elution pattern on cobrotoxin‐Sepharose and chromatography on DEAE‐cellulose column.

Gel filtration patterns on a Sepharose 6B column revealed that the soluble complexes formed from non‐precipitating antibody and HNB‐cobrotoxin at a different molar ratio all emerged in the void volume, indicating that the molecular weight of the soluble complex is around 4,000,000 or larger. Unreacted free non‐precipitating antibody coincided with the peak of IgG and was proved to be free from HNB‐cobrotoxin. The molar ratio of antibody to antigen for the soluble complex was found to be 0.79 to 0.97 indicating that 1.58–1.94 molecules of non‐precipitating antibody are bound to HNB‐cobrotoxin instead of three molecules as in the case of precipitating antibody.
PREPARATION AND PROPERTIES OF TRITIATED HUMANβ‐ENDORPHIN WITH HIGH SPECIFIC RADIOACTIVITY
Authors: Houghten Richard A. , Li Choh Hao
Published: August 2010

Tritiated humanβ‐endorphin, specifically labelled at Tyr27, has been prepared with 50 Ci/mmol. Various physicochemical investigations indicated that tritiated peptide is identical with the nativeβh‐endorphin. In addition, opiate activity of the tritiated product possesses the same potency as the native peptide.
CONFORMATIONAL ANALYSIS OF N‐(tert.‐AMYLOXYCARBONY‐l‐PROLINE IN THE SOLID STATE AND IN SOLUTION
Authors: BENEDETTI ETTORE , CIAJOLO ANNA , BLASIO BENEDETTO DI , PAVONE VINCENZO , PEDONE CARLO , TONIOLO CLAUDIO , BONORA GIAN MARIA
Published: August 2010

The solid‐state conformational analysis of t‐AOC‐l‐Pro‐OH** has indicated that the molecules are not folded up to form an oxy‐C7 peptide conformation, but rather that they are held together through intermolecular O‐H. 0 = C (urethane) hydrogen bonds. The tertiary amide bond is in the cis configuration. In solvents of high polarity strongly solvated species largely predominate. In cyclohexane solution non‐associated and associated (involving the carboxyl C = O as the proton acceptor) species are simultaneously present. Obviously, the extent of association increases with increasing solute concentration. The amount of the oxy‐C7 form, if any, should be extremely small. It is also demonstrated that CD measurements alone can lead to an incorrect picture of the conformational preferences of amino acid derivatives and small peptides in solution.
STUDIES ON PEPTIDES LXXXI. Application of a New Arginine Derivative, NG‐Mesitylene‐2‐Sulfonylarginine, to the Synthesis of Substance P and Neurotensin
Authors: YAJIMA HARUAKI , AKAJI KENICHI , MITANI KAZUYA , FUJII NOBUTAKA , FUNAKOSHI SUSUMU , ADACHI HIDEKI , OISHI MARIKO , AKAZAWA YOSHIHARU
Published: August 2010

A new devised arginine derivative, NG‐mesitylene‐2‐sulfonylarginine, Arg(Mts), was employed for the synthesis of hypothalamic substance P and neurotensin. The former was obtained in 74% yield by treatment of the protected undecapeptide amide, Z ‐ Arg(Mts) ‐ Pro ‐ Lys(Z) ‐ Pro ‐ Gln ‐ Gln ‐ Phe ‐ Phe ‐ Gly ‐ Leu ‐ Met(O)‐NH2, with methanesulfonic acid in the presence of anisole followed by reduction of the sulfoxide with 2‐mercaptoethanol. The latter was obtained in 54% yield by the similar treatment of the protected tridecapeptide ester, Z‐Pyr‐Leu ‐ Tyr ‐ Glu(OBzl) ‐ Asn ‐ Lys(Z)‐Pro‐Arg(Mts) ‐ Arg(Mts) ‐ Pro ‐ Tyr‐Ile‐Leu‐OBzl, with methanesulfonic acid. As scavenger, a mixture of anisole‐thioanisole‐o‐cresol (1:1:1, by vol.) was employed to suppress the side reaction, O‐mesitylene‐2‐sulfonation of the Tyr residue.
RABBIT LUTROPIN: PREPARATION, CHARACTERIZATION OF THE HORMONE, ITS SUBUNITS AND RADIOIMMUNOASSAY
Authors: WARD DARRELL N. , DESJARDINS CLAUDE , MOORE WILLIAM T. , NAHM HYUN S.
Published: August 2010

The purification of rabbit lutropin is described. A product with a potency of 1.53 × NIH‐LH‐Sl was obtained as assayed by the ovarian ascorbic acid depletion assay. In a homologous radioimmunoassay, which is described, rabbit lutropin has a potency 4.83 × NIH‐LH‐Sl. In a radioligand assay, utilizing labeled ovine lutropin as the trace, the relative potency was 0.47 × NIH‐LH‐Sl measured by 50% inhibition comparison since rabbit lutropin response in this system did not parallel ovine lutropin.

A counter‐current distribution procedure for separation of rabbit lutropin subunits is described. Amino acid composition of the isolated subunits and intact rabbit lutropin was determined. The carbohydrate composition of the latter is presented; only amino sugar determinations are available for the subunits. The NH2‐terminal amino acids are phenylalanine (alpha subunit) and alanine (beta subunit). Preliminary data on COOH‐terminal amino acids are provided.
OXIDATION OF THE SULFHYDRYL FORMS OF INSULIN A‐CHAIN AND B‐CHAIN
Authors: PAYNOVICH RICHARD C. , CARPENTER FREDERICK H.
Published: August 2010

A modified procedure for the preparation of the S‐sulfonates of the A‐ and B‐chains of insulin and their conversion to the sulfhydryl forms by tri‐n‐butyl‐phosphine is described. Air oxidation of the sulfhydryl forms of the A‐chain in dilute solution (0.2 mg/ml) either in the presence or absence of urea at pH 9.0 yields primarily monomeric, intrachain disulfides. Similar treatment of the reduced B‐chain yields monomeric, intrachain disulfide in 7 m urea but a large number of oligomeric, interchain disulfides in the absence of urea. Electrolytic reduction of insulin in 7 m urea at pH 8.5, followed by oxidation of the sulfhydryls in dilute solution in 7 m urea at pH 9.0 yields primarily a mixture of the monomeric, intrachain disulfides of the A‐chain and of the B‐chain which can be separated by chromatography on Sp‐Sephadex in acidic urea. The rate of the oxidation of the sulfhydryls of the two separate chains was much slower and less complete than that reported for the two chains crosslinked by the carbonylbismethionyl residue.
USE OF THIOCYANIC ACID TO FORM 2‐THIOHYDANTOINS AT THE CARBOXYL TERMINUS OF PROTEINS
Authors: DWULET FRANCIS E. , GURD FRANK R. N.
Published: August 2010

The chemistry of the formation of 2‐thiohydantoins on the carboxyl terminal of peptides or proteins was investigated. It was found that thiocyanic acid was much more reactive for the formation of 2‐thiohydantoins than were the thiocyanate salts. The physical reasons for this observation are explained. The kinetics of the reaction of a number of proteins, and some of their fragments, with thiocyanic acid were also determined. Simple and safe procedures for the preparation of anhydrous thiocyanic acid solutions were devised. The prospective application of these procedures to sequencing from the carboxyl terminal of a polypeptide is discussed.
SYNTHESIS AND BIOLOGICAL EFFECT OF THE C‐TERMINAL PENTAPEPTIDE AMIDE OF AVIAN PANCREATIC HORMONE III (APP)
Authors: KANELLIS PANAYIOTIS , DYCKES DOUGLAS F. , HAZELWOOD ROBERT L.
Published: August 2010

Model building studies and analogies drawn from peptides of similar biological activity have indicated that the C‐terminus of avian pancreatic hormone III may possess significant biological information. To test this hypothesis, the C‐terminal pentapeptide amide sequence has been synthesized by the Merrifield method. The synthesis, purification and characterization of this compound are reported here in detail. In vivo studies indicate that this synthetic segment possesses none of the secretogogic activity of the parent hormone; rather, it reduces “gastric” secretion levels even in the presence of the intact hormone.
STUDIES ON PROTEIN FOLDING, UNFOLDING AND FLUCTUATIONS BY COMPUTER SIMULATION III. Effect of Short‐Range Interactions
Authors: GO NOBUHIRO , TAKETOMI HIROSHI
Published: August 2010

The theoretical model of proteins on the two‐dimensional square lattice, introduced previously, is extended to include the specific short‐range interactions. Attractive long‐range interactions with various specificities and non‐specific repulsive long‐range interactions in the form of self‐avoidance of the polymer chain are also operative in the model. Dynamics of the model protein is studied by a Monte Carlo method. The short‐range interactions are found to accelerate the folding and unfolding transitions. Non‐specific part of the attractive long‐range interactions have a competing effect of decelerating the transitions. When the short‐range interactions are weighted beyond a certain extent over the attractive long‐range interactions, the all‐or‐none character of the folding and unfolding transitions is destroyed. How the destruction proceeds is quantitatively expressed in terms of the S‐H curves. The limiting case of dominance of the specific short‐range interactions over the attractive long‐range interactions is studied in detail. The lattice polymer in this limit does not behave like a globular protein at all. This observation leads to a reexamination of the currently popular notion of the dominance of the short‐range interactions. A new concept of consistency is proposed to replace it. Possible mechanisms of the acceleration of the transitions by the specific short‐range interactions are discussed.
ADRENOCORTICOTROPIN 52*. Synthesis and Biological Activity of Adrenocorticotropic Peptides with Cystine Bridges
Authors: BLAKE JAMES , RAO A. JAGANNADHA , LI CHOH HAO
Published: August 2010

Three analogs of the amino terminal nonadecapeptide of adrenocorticotropin which incorporate cystine bridges between positions (5, 10), (3, 10), or (2, 10) have been synthesized. All of the peptide analogs showed reduced biological activity; however, the peptide with the 5, 10 cystine bridge was shown to possess significantly higher lipolytic activity in rat fat cells than the peptides with a 3, 10 or 2, 10 cystine bridge.
MOLAR ABSORPTIVITY AND A 1 cm 1% VALUES FOR PROTEINS AT SELECTED WAVELENGTHS OF THE ULTRAVIOLET AND VISIBLE REGIONS. XVII
Authors: KIRSCHENBAUM DONALD M.
Published: August 2010

A table of A 1 cm 1% values and molar absorptivity values for more than 150 proteins is given. The conditions used to obtain these values are also given.
SEPARATION OF OPIOID PEPTIDES UTILIZING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
Authors: LEWIS RANDOLPH V. , STEIN STANLEY , UDENFRIEND SIDNEY
Published: August 2010

Chromatographic procedures have been developed for resolving all of the known enkephalins and endorphins on a single column. The effect of eluant pH on the retention times and separation of the enkephalins and β‐endorphin was determined. By combining these separations with a sensitive radioreceptor assay it is possible to assay all of the opioid peptides in the pituitary gland or in various regions of the brain from individual small laboratory animals.
UREA AND GUANIDINE HYDROCHLORIDE INDUCED DISSOCIATION AND DENATURATION OF BACTERIOPHAGE F2 CAPSID
Authors: KITCHELL BARBARA B. , HENKENS ROBERT W.
Published: August 2010

A single, low molecular weight protein is found after urea or guanidine hydrochloride (Gdn.HCl) treatment of empty capsids derived from bacteriophage f2. The final product of denaturation is apparently a monomer, existing as a random coil in ≥ 4.0 M Gdn.HCl but in a less extended form in 8.0 M urea. In contrast, an 11 S protein component is isolated after treatment of the intact virus with 4.0 M Gdn.HCl (Zelazo & Haschemeyer, 1969), indicating that RNA plays a role in stabilizing larger subunits. Denaturation by Gdn.HCl occurs in two stages as measured by changes in CD and Stokes radius: dissociation that involves a structural perturbation of aromatic side chains, followed by a major, cooperative transition that evidently results in the loss of all noncovalent structure. Denaturation by urea appears to be a much less cooperative process that occurs in several steps over a wide range of urea concentration (1–7 M). In both urea and Gdn.HCl, dissociation into subunits begins at a lower concentration of denaturant than the major changes in conformation.
SYNTHESIS OF MODEL COMPOUNDS RELEVANT TO THE ACTIVE‐SITE‐DIRECTED INACTIVATION OF L‐ASPARAGINASE BY 5‐DIAZO‐4‐OXO‐L‐NORVALINE*
Authors: CHANG PAULINE K. , LACHMAN LAWRENCE B. , HANDSCHUMACHER ROBERT E.
Published: August 2010

Earlier work has shown that 5‐diazo‐4‐oxo‐l‐norvaline (DONV) irreversibly inactivates the l‐asparaginase from E. coli by formation of a covalent bond in the region of the active site. Model compounds have been prepared to study this acid‐labile covalent bond tentatively assigned to a serine or possibly a threonine residue in a decapeptide isolated from 14C‐DONV‐inactivated enzyme. Appropriately blocked DONV was found to alkylate methanol, and the hydroxyl function of blocked serine or threonine in the presence of boron trifluoride. The labile β‐ketoethers thus formed were reduced to the more stable β‐hydroxyethers. Facile lactonization of these 5‐substituted‐4‐hydroxy‐l‐norvalines was observed. The diastereoisomers of both the lactonized and open forms of 5‐methoxy‐4‐hydroxy‐l‐norvaline and related 4‐hydroxy‐l‐2‐amino acids of similar length were distinguishable on the amino acid analyzer. The β‐hydroxyethers derived from serine and threonine were hydrolyzed with acid and yielded the expected cleavage products. When the β‐ketoether was reduced by sodium borohydride prior to deblocking, in addition to the β‐hydroxyether, N‐blocked amino alcohols were also formed, yielding a complex mixture of products.
SYNTHETIC ENKEPHALINS Addicting Properties and Conformational Studies in Solution
Authors: FILIPPI BRUNO , GIUSTI PIERO , CIMA LORENZO , BORIN GIANFRANCO , RICCHELLI FERNANDA , MARCHIORI FERNANDO
Published: August 2010

The addicting properties of [Leu5]‐enkephalin in mice are conserved in the l‐Ser3 analogue and lost both in the l‐Ser2 analogue and in all the l‐Cha4 derivatives of the above peptides. Fluorescence measurements in water show the presence of hydrogen‐bonded tyrosyl OH groups in [Leu5] ‐enkephalin and in its l‐Ser2 analogue. The Phe4/Cha replacements do not influence these equilibria, but they affect the near u.v. dichroism of the hydrogen bonded tyrosyl residues. In the peptide absorption region in water solution, only [Leu5]‐enkephalin and its cyclohexylalanyl derivative show a positive dichroism towards high frequencies, which is maintained in 8 M urea. No clear relation is found between conformations) in solution and biological activity. A II' β‐turn, with residues in positions 2 and 3 at the corners, is suggested for the conformation of enkephalin bound to the receptors involved in the bioassay here used.
SYNTHESIS OF ANALOGS OF THE SERUM THYMIC NONAPEPTIDE, FACTEUR THYMIQUE SERIQUE (FTS) Part I
Authors: BLANOT DIDIER , MARTINEZ JEAN , AUGER GENEVIEVE , BRICAS EVANGHELOS
Published: August 2010

Analogs of FTS (Facteur Thymique Sérique), < Glu‐1‐Ala‐2‐Lys‐3‐Ser‐4‐Gln‐5‐Gly‐6‐Gly‐7‐Ser‐8‐Asn‐9, a circulating thymic factor, were prepared by replacing the amino acid 8 9 residues in positions 1, 2, 8 and 9, or by shortening the nonapeptide chain at the N‐ or C‐terminal end. These peptides were synthesized by two different schemes using the conventional synthesis in solution.
A NEW ARYLATING AGENT, 2‐CARBOXY‐4,6‐DINITROCHLOROBENZENE Reaction with Model Compounds and Bovine Pancreatic Ribonuclease
Authors: BELLO JAKE , IIJIMA HERBERT , KARTHA GOPINATH
Published: August 2010

The reagent 2‐carboxy‐4,6‐dinitrochlorobenzene (CDNCB) reacts with the imino, amino and sulfhydryl groups of model compounds. At pH 8.2, sulfhydryl groups react much faster than do amines. Nα‐Acetylhistidine, Nα‐acetyltyrosine and Nα‐acetyltryptophan do not react. Poly (l‐Lysine) and poly (dl‐lysine) react about 50 times as fast as does Nα‐acetyllysine. A dichloroanalog, 6‐carboxy‐2,4‐dinitro‐1,3‐dichlorobenzene, shows stepwise reactivity with amines. With bovine pancreatic ribonuclease, which contains no sulfhydryl, CDNCB reacts preferentially with the e‐amino of Lys‐41 at 450 times the rate with the e‐amino of Nα‐acetyllysine. The preferential reactivity at Lys‐41 is discussed in relation to the pK of Lys‐41, the cationic character of the active site cleft, and the mechanism of RNAase action on substrates.
EFFECT OF SUCCINYLATION ON THE OLIGOMERIC STRUCTURE OF GLYCININ
Authors: RAO A.G. APPU , RAO M.S. NARASINGA
Published: August 2010

By varying the ratio of succinic anhydride to the protein, glycinin, one of the major fractions of soybean proteins, is succinylated to various levels. Sedimentation velocity experiments indicate the dissociation of the protein due to succinylation. Viscosity increases and a blue shift occurs in the absorption spectrum. The rate of proteolysis increases. Both dissociation and denaturation of the protein appear to occur. The effect of succinylation on glycinin and arachin, the major protein of groundnuts, appears to be different.
METHIONINE ENKEPHALIN AND ISOSTERIC ANALOGUES
Authors: HUDSON DEREK , SHARPE ROBERT , SZELKE MICHAEL
Published: August 2010

Biological activities are reported for two different types of analogues of methionine enkephalin. Cyclic analogues, bridged between the amino‐ and carboxy‐ terminals of the parent peptide, are inactive. In contrast, significant levels of activity are displayed by linear isosterically modified analogues in which the Tyr1 ‐Gly2 peptide bond is replaced by either ‐CH2NH‐ or ‐CH2 CH2‐. Similar replacements of the Gly2‐Gly3 peptide bond yield compounds with much reduced potency. These modifications serve as useful probes of the receptor conformation. Based on these findings, a model is proposed for interaction between enkephalin and its receptor.
ISOLATION AND CHARACTERIZATION OF β‐LIPOTROPIN AND ADRENOCORTICOTROPIN FROM TURKEY PITUITARY GLANDS*
Authors: CHANG WEN‐CHANG , CHUNG DAVID , LI CHOH HAO
Published: August 2010

β‐Lipotropin and corticotropin have been isolated in highly purified form from turkey pituitary glands. The isolated hormones were characterized by NH2‐terminal residue, amino acid and sequence analyses. Their hormonal activity and immunoactivity were also investigated.
SYNTHESIS OF γ‐L‐GLUTAMYL‐TAURINE*
Authors: SEBESTYÉN F. , FURKA Á. , FEUER L. , GULYÁS J. , SZÓKÁN GY.
Published: August 2010

Glu(Tau), a bioactive substance previously isolated from the protein free aqueous extract of bovine parathyroid powder, has been synthesized. The intermediate derivative Z‐Glu(Tau)‐OBzl was prepared in three different ways from Z‐Glu‐OBzl and (1) cystamine by using the mixed anhydride method followed by oxidation, (2) Tau by the active ester procedure via Z‐Glu(ONp)‐OBzl, (3) Tau applying mixed anhydride coupling. The protecting groups were removed by hydrogenolysis.
PURIFICATION OF PEPTIDES: AN EFFICIENT PROCEDURE FOR THE SEPARATION OF PEPTIDES FROM AMINO ACIDS AND SALT
Authors: BÖHLEN PETER , CASTILLO FRED , LING NICHOLAS , GUILLEMIN ROGER
Published: August 2010

A novel method for the separation of peptides from amino acids and salts has been developed. Separation is achieved by passage of the sample through a column of octadecasilyl‐silica (ODS). Peptides, but not amino acids and salts, are strongly retained by ODS in an aqueous mobile phase and can be recovered by elution with an aqueous‐alcoholic mobile phase. The method is applicable to most peptides and is fast and simple. Moreover, it is characterized by good recovery yields and high sample capacity.
SUPERIOR SWELLING PROPERTIES OF RESINS OF POLY‐N‐ACRYLYLDIALKYLAMINES OVER POLYSTYRENE IN SOLVENTS FOR PEPTIDE SYNTHESIS
Authors: STAHL GLENN L. , SMITH CLARK W. , WALTER RODERICH
Published: August 2010

Three beaded poly‐N‐acrylyldialkylamine resins have been systematically compared with polystyrene‐co‐1%‐divinylbenzene for their ability to interact with solvents that are useful in peptide synthesis. The three resins have the same cross‐linking monomer, N,N1‐bisacrylyl‐1,2‐diminoethane, and functionalizing monomer, N‐acrylyl‐1,6‐diaminohexane hydrochloride. They differ from one another in the compositions of the base monomer, degree of cross‐linking (DC), quantity of functionalizing monomer, or monomer dilution ratio (MDR, ratio of inert solvent to monomers by weight). Resin1is poly‐N‐acrylylpyrrolidine containing 0.75 mmol/g of amino function with DC 4.4 and MDR 4; resin2is poly‐N‐acrylyldimethylamine containing 0.75 mmol/g of amino function with DC 4.4 and MDR 4; resin3is poly‐N‐acrylyldimethylamine with DC 10 and MDR 6.8. Swelling was the property used as the measure of solvation in a given solvent for the macroscopically insoluble polymers. In their protonated or acylated forms resins 1—3 exhibit favorable swelling properties in methanol, ethanol, 2,2,2‐trifluoroethanol, 2‐propanol, acetic acid, and water, solvents in which polystyrene either swells little or not at all. In addition, the resins swell in methylene chloride, chloroform and dimethylformamide, solvents commonly used in the Merrifield method of solid‐phase peptide synthesis, to about the same extent as polystyrene. The favorable swelling properties of the poly‐N‐acrylyldialkylamine resins should not only allow the use of most of the techniques developed for the solid‐phase method, but should allow the invention and application of new techniques that rely on aqueous or other polar solvents.
β‐ENDORPHIN: HYPERTHERMIA IN MICE BY INTRAVENOUS INJECTION
Authors: TSENG LIANG‐FU , LI CHOH HAO
Published: August 2010

Effects of intravenous β‐endorphin on body temperature and body weight loss were studied in naive and morphine‐dependent mice. β‐Endorphin at doses 2.6–25.5 mg/kg injected intravenously caused hyperthermia in naive mice as well as in morphine‐dependent mice. In addition, β‐endorphin and morphine reduced body‐weight loss during the morphine withdrawal.
RACEMIZATION IN PEPTIDE SYNTHESIS
Authors: BENOITON N. LEO , KURODA KEIJI , CHEN FRANCIS M.F.
Published: August 2010

A laboratory experiment involving the coupling of N‐benzoylamino acids with methyl Nε‐benzyloxycarbonyl‐L‐lysinate using various methods is described. The extents of racemization are determined by analysis for the protected diastereomeric dipeptide ester products by quantitation of the separated ester methyl proton peaks of their nuclear magnetic resonance (60 MHz) spectra. Synthesis of the starting materials and additional exercises are included as options.