bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isohalic sorption isotherms.
Authors: POULTER R. G. , DOE P. E. , OLLEY JUNE 
Published: August 2010

SummaryIsohalic sorption isotherms of cod (Gadus morrhua) are used, in conjunction with growth data for dun mould (Wallemia sebi), to predict the shelf life of dried salted fish in tropical climates. Measured shelf‐lives of several fish species processed and stored by traditional methods are in agreement with the predictions.
CONFORMATION OF ANTIBIOTIC PROTEIN, NEOCARZINOSTATIN, STUDIED BY PLANE POLARIZED INFRARED SPECTROSCOPY, CIRCULAR DICHROISM AND OPTICAL ROTATORY DISPERSION
Authors: Maeda Hiroshi , Shiraishi Hiroyuki , Onodera Shinji , Ishida Nakao 
Published: August 2010

The peptide backbone and aromatic side chain conformations of antitumour antibiotic protein, neocarzinostatin and its derivative tetra‐S‐carboxymethyl neocarzinostatin, have been studied using the ultraviolet circular dichroism (CD), optical rotatory dispersion (ORD) and plane polarized infrared spectroscopy.The near ultraviolet CD and ORD indicated multiple contributions from side chain chromophores (π → π*) suggesting buried state (resulting asymmetric property) of phenylalanyl and tyrosyl and perhaps cystine residues in neocarzinostatin. These results are quite accordant with that of chemical inactivity of the tyrosyl and cystinyl residues in the antibiotic. No clear band was assigned for contribution of tryptophyl residue.The results of the infrared spectroscopy at amide I and II have been found more useful in the present study for the analysis of peptide backbone conformations, which indicated the presence of cross β‐conformation, while the far ultraviolet CD and ORD spectra were atypical and unable to be interpreted.The results of the examination of amino acid sequence and composition support the finding of infrared studies.The assumption that neocarzinostatin possesses a rigid overall conformation can be explained by the above results and by our separate findings of its peculiar resistances to disulfide bond reductions in aqueous system and hydrolyses by proteolytic enzymes.
A STUDY OF THE CYSTINE RESIDUES IN BOMBYX MORI AND OTHER SILKS
Authors: Earland Christopher , Robins Simon P. 
Published: August 2010

Silks representative of the three subfamilies of Bombycidae have been studied and it has been found that they all contain cystine residues. The amount present varies, but irrespective of the country of origin is constant for a given species. In all cases the cystine content of the sericin was found to be at least twice that of the fibroin, which suggests that disulphide cross‐linking does not contribute to the insolubility of the latter.The cystine content of Bombyx mori fibroin is 10.0 μ mole/g and this work has shown that at least one third of this cystine is present in the sequenceArg‐Ala‐Leu‐Pro‐Cys‐Asn‐Val‐CysAlthough such a small cystine‐containing ring has not previously been reported as occurring in proteins, it is concluded that on stereochemical grounds the structure is sound.
β‐LYTIC PROTEASE, A NEUTRAL SORANGIOPEPTIDASE*
Authors: Oza Narendra B. 
Published: August 2010

The specificity of β‐lytic protease of Sorangium is found to be similar to neutral proteases of bacterial origin. The β‐enzyme did not hydrolyze any of the common esters of pancreopeptidases; however, an affinity for the peptide bond between R and R1 in the molecular arrangement X‐R‐R1‐NH2 was shown. The substitution occurred at the N‐terminal of a hydrophobic amino acid whose carboxyl end was not terminal. 3‐(2‐furyl‐acryloyl)‐glycyl‐L‐leucine amide was the substrate of choice since accurate spectrophotometric rate assays could be accomplished with this substrate.A close relationship existed between the mammalian proteases and Sorangium proteases. The β‐enzyme was similar to carboxypeptidase (non‐serine protease) in some respects, and the α, δ, enzymes of Sorangium were, to some extent, similar to serine proteases of mammalian origin. In agreement with the nomenclature of other neutral proteases, a more specific name of ‘Neutral Sorangiopeptidase’ has been suggested.
THE CRYSTAL AND MOLECULAR STRUCTURE OF YEAST L‐LACTATE DEHYDROGENASE (CYTOCHROME b2):
Authors: Olive J. , Barbotin J. N. , Risler J. L. 
Published: August 2010

An electron microscopy study of yeast cytochrome b2 has been performed on two different crystalline forms by negative staining and freeze‐etching.The overall dimensions of the tetrameric molecule were deduced from the study of the trigonal (DNA‐free) crystals, and were found to be 97 × 60× 56 Å. These dimensions impose some restrictions to the possible packings of the molecules in the tetragonal (DNA‐containing) crystals. Together with the optical diffraction pattern of the micrographs and results of earlier X‐ray diffraction studies, these data permit the conclusion that, at 20 Å resolution, cytochrome b2 is a true tetramer with molecular symmetry 222.
A STUDY OF THE ACTIVE CENTER OF TRYPSINOGEN BY COMPARATIVE AFFINITY CHROMATOGRAPHY OF TRYPSINOGEN, α‐, β‐, ψ‐TRYPSINS, DIP‐TRYPSIN, CHYMOTRYPSINOGEN, α‐CHYMOTRYPSIN AND ELASTASE
Authors: Chauvet Jacqueline , Acher Roger 
Published: August 2010

Affinity chromatography of α‐, β‐, ψ‐trypsins, chymotrypsin and elastase on trypsin inhibitor (bovine Kunitz inhibitor) coupled with Sepharose has shown that, despite the conformational similarity, elastase is not adsorbed in contrast to trypsins and chymotrypsin. This result might suggest that the specificity site is involved in the binding. On the other hand, because inactive DFP‐treated trypsin is not adsorbed, the catalytic site and especially Ser‐195 might also be necessary for the association.Chrymotrypsinogen is not adsorbed on the inhibitor‐Sepharose, but trypsinogen is retarded at pH 7.0 and the delay is increased at pH 8.1. The behaviour of trypsinogen on inhibitor‐Sepharose, in contrast to those of DIP‐trypsin and chymotrypsinogen, suggests that both catalytic and specificity sites are necessary for the binding and that these sites are partially pre‐existent in trypsinogen.
THE EFFECTS OF COMBINING TWO DIFFERENT ALCOHOLS ON THE HEAT‐INDUCED REVERSIBLE DENATURATION OF RIBONUCLEASE
Authors: Gerlsma Sicco Y. , Stuur Elzo R. 
Published: August 2010

The effects of combining two different alcohols on the transition temperature of ribonuclease were investigated.It appears that at 60°C the combined effects on the transition temperature of ribonuclease of two different alcohols are equal to the algebraic sum of the effects of each individual alcohol. This holds true for a combination of two monohydric alcohols, two polyhydric alcohols and a combination of a monohydric and a polyhydric alcohol.At lower temperatures only the effects of the combinations of two polyhydric alcohols show additivity. The combined effect of a polyvalent alcohol and a monovalent alcohol at low temperature is surprisingly higher than the algebraic sum of the effects of the individual alcohols.The polyhydric alcohol enhances the hydrophobic effect of the monovalent alcohol for temperatures up to 50°C. Obviously the polyhydric alcohol perturbs the water structure at these low temperatures, which leads to the intensifying of the interhydrophobic interactions.Furthermore, the combined effect of two different monovalent alcohols with different hydrophobic effects does not show additivity at low temperatures. The single (OH) group of the weakest hydrophobic alcohol enhances the hydrophobic effect of the potentially strongest hydrophobic alcohol.
MALEYLATION OF ALKALINE MESENTERICOPEPTIDASE
Authors: Genov Nicolay , Shopova Maria 
Published: August 2010

Seven of the eight e‐amino groups of the lysyl residues in alkaline mesentericopeptidase were modified when the enzyme was treated with maleic anhydride. Some conclusions about the degree of exposure to the solvent of these amino acid side chains were made. The results are discussed in relation to the X‐ray crystallographic model of subtilisin type BPN.The maleylation of alkaline mesentericopeptidase caused a loss of its elastolytic activity while the rate of cleavage of casein was slightly increased. Maleyl‐enzyme has the same activity as the native mesentericopeptidase with the synthetic ester substrates Nα‐tosyl‐L‐arginine methyl ester and N‐acetyl‐L‐tyrosine ethyl ester. It was concluded that the additional negatively charged groups were introduced outside the primary binding sites for small substrates.The effects of varying the salt concentration on mesentericopeptidase activities were studied and conclusions about the forces responsible for the formation of the enzyme‐substrate complexes were drawn.
REDUCTION AND REOXIDATION OF BOVINE PROINSULIN. EFFECT OF pH, ZINC IONS, TEMPERATURE AND CONCENTRATION
Authors: Markussen Jan , Heding Lise G. 
Published: August 2010

The influence of pH, temperature and the concentrations of zinc ions and reduced proinsulin upon the yields of reoxidized proinsulin were studied using the insulin radioimmunoassay. The optimal conditions were found to be pH 8.5, absence of zinc ions and a low protein concentration. However, even at a concentration of reduced proinsulin of 1.47 μM, the reoxidized proinsulin did not compete with 125I‐insulin for the insulin antibodies as strongly as did genuine proinsulin. At high concentrations of reduced proinsulin (14.7 μM), the yield increased with decreasing temperature; at a 10‐times lower concentration the temperature had no influence upon the yields. Adsorption of reduced prosinulin to glassware was either irreversible or had a denaturing effect rendering the products immunologically inactive. Spontaneous reoxidation of reduced proinsulin is a rather delicate process, and the optimal conditions are different from those present in vivo.When the reduction of proinsulin was carried out at a concentration of 31.5 μM, zinc ions were found to stabilize the reduced protein against denaturation and precipitation for more than 24 hours. However, at this concentration, reduced proinsulin is in a thermodynamic ally unstable state, both with and without zinc.
A POTENTIOMETRIC AND CD STUDY ON THE β‐RANDOM COIL TRANSITION OF POLY‐L‐TYROSINE IN AQUEOUS SOLUTION
Authors: Cosani A. , Palumbo M. , Terbojevich M. , Peggion E. 
Published: August 2010

The pH induced coil‐β transition of poly‐L‐tyrosine has been investigated by potentiometric and CD techniques. The “poly‐electrolyte” plot pKα vs. a shows the characteristic behaviour of polypeptides undergoing a conformational transition. CD measurements carried out on samples of the polymer solution under titration indicated that the polymer conformation changes within the same range of degrees of ionization as the titration curve exhibits the characteristic “hump”. Taking into account literature data on the aggregation process during the titration, the conclusion was made that β‐structure formation parallels aggregation.The stability of the β‐structure of (L‐Tyr)r was found to decrease by increasing the temperature to 60°C. These results are discussed in terms of the solvation effects of the polymer side‐chains.
THE ENNIATIN IONOPHORES. CONFORMATION AND ION BINDING PROPERTIES
Authors: Ovchinnikov Yu. A. , Ivanov V. T. , Evstratov A. V. , Mikhaleva I. I. , Bystrov V. F. , Portnova S. L. , Balashova T. A. , Meshcheryakova E. N. , Tulchinsky V. M. 
Published: August 2010

The ability of enniatins to bind alkali metal, alkaline earth metal and certain transition metal ions in solution has been investigated. The complexes have been shown to form in 1:1, 2:1 and 3:2 macrocycle:cation ratios; their stability constants have been determined, and the conditions favoring their formation have been established. The enniatins were shown to be complexones of very wide spectrum, displaying low metal ion selectivity in alcoholic solutions.Two basic spatial forms, the non‐symmetric N3 form (in nonpolar solvents) and the symmetric P form (in polar solvents) have been disclosed and proposals made as to their conformational parameters. The molecular structure of the enniatin complexes has been established. Independent of the complexed ion species, of the complex stoichiometry, or of the type of solvent, the enniatin backbone of the complex is in the P form. In the 1:1 complexes, the ion is accommodated in the molecular cavity, forming iondipole bonds with all the amide and ester carbonyls. The depsipeptide chain of the enniatins is flexible, permitting “adaptation” of the complexone to the size of the ion, and thus explaining the low selectivity of these complexones. In the 2:1 and 3:2 complexes the cation is sandwiched in between two molecules of the antibiotic at the symmetry axis and interacts mainly with the N‐methylamide carbonyls. In these “sandwich” complexes the cation is much better screened from the anion and solvent than in the equimolar complexes and is highly soluble in organic solvents.The data presented here may serve as basis for interpreting the dependence between the structure, metal complexing behavior and membrane‐affecting properties in the series of the naturally occurring enniatin ionophores and their synthetic analogs.
THERMOPHILIC AMINOPEPTIDASE FROM BACILLUS STEAROTHERMOPHILUS.
Authors: Balerna M. , Zuber H. 
Published: August 2010

1. In mesophilic cells (37°C culture) of B. stearothermophilus a high molecular weight aminopeptidase (APIm) was found in the “membrane” fraction after lysozyme treatment and ultrasonication. APIm, which is also present in 55°C cells but in a 30‐fold lower amount, could be extracted from the “membranes” by carbonate‐bicarbonate buffer pH 9.6 and was further purified. APIm has a mol. wt. of about 400,000 and has an oligomeric structure (mol. wt. of subunits 46,000 ± 3,000). The “membrane‐bound” and the soluble enzyme differ in thermostability: The former bound‐enzyme is more thermostable. Specificity: Dipeptides are poor and tri‐ and tetrapeptides are good substrates with Gly, Leu, Ala or Met at the N‐terminus. In tripeptides the enzyme splits preferentially the first (N‐terminal) peptide bond.2. Aminopeptidase III (APIII), which is synthesized in 37°C cultures of B. stearothermophilus in a 10‐fold higher amount than in 55°C cultures, was purified to homogeneity by a four‐step purification procedure. Mol. wt. of APIII: 108,000 and of the subunits 47,500 ± 3,000 (dimer). APIII is not thermostable at 60–70°C. The amino acid composition of APIII for some amino acids (Lys, His, Thr, Pro, Ala, Met, Ile, Tyr, Phe) is very similar to the composition of APII, and for Lys, His, Arg, Thr, Glu, Pro, Phe it is similar to that for thermophilic API. The most striking feature of this enzyme is its specificity as aminotripeptidase.
STUDIES ON A PROTAMINE (GALLINE) FROM FOWL SPERM.
Authors: Nakano Minoru , Tobita Tohru , Ando Toshio 
Published: August 2010

Galline, a protamine from rooster sperm nuclei, has already been separated into its components, G‐I‐G‐VIII. The amino acid composition of the homogeneously purified fraction G‐I is determined decisively to be Arg11, Ser2, Gly3, Val1 and Tyr2, and the molecular weight is 2,908 as hydrochloride. The complete amino acid sequence was deduced as follows from the results of analyses of the tryptic and chymotryptic peptides: H‐Ser‐Gly‐Gly‐Val‐Arg‐Arg‐Arg‐Arg‐Tyr‐Gly‐Ser‐Arg‐Arg‐Arg‐Arg‐Arg‐Arg‐Arg‐Tyr‐OH.Another purified fraction, G‐V, has the amino acid composition, Arg24, Thr1, Ser8, Gly3, Ala2, Pro2 and Tyr2 as described previously, and the molecular weight 6,274 as hydrochloride. The complete amino acid sequence was established by combining analytical results of tryptic, chymotryptic and thermolysin peptides as well as those of carboxypeptidase and leucine aminopeptidase digestion as follows: H‐Ala‐Arg‐Tyr‐Arg‐Ser‐Gly‐Arg‐Ser‐Arg‐Ser‐Arg‐Arg‐Thr‐Arg‐Arg‐Arg‐Arg‐Ser‐Pro‐Arg‐Ser‐Arg‐Gly‐Arg‐Ser‐Pro‐Arg‐Arg‐Arg‐Arg‐Ser‐Arg‐Arg‐Arg‐Arg‐Arg‐Tyr‐Gly‐Ser‐Ala‐Arg‐Arg‐OH.
STUDIES ON THE CONFORMATION AND INTERACTIONS OF ELASTIN: NUCLEAR MAGNETIC RESONANCE OF THE POLYHEXAPEPTIDE
Authors: Urry D. W. , Ohnishi T. , Long M. M. , Mitchell L. W. 
Published: August 2010

Synthesis, proton magnetic resonance and carbon‐13 magnetic resonance characterizations, including complete assignments, are reported for the polyhexapeptide of elastin, HCO‐Val‐(Ala1‐Pro2‐Gly3‐Val4‐Gly5‐Val6)18‐OMe. Temperature dependence of peptide NH chemical shifts and solvent dependence of peptide C‐O chemical shifts have been determined in several solvents and have been interpreted in terms of four hydrogen bonded rings for each repeat of the polyhexapeptide. The more stable hydrogen bonded ring is a β‐turn involving Ala1 C‐O…HN·Val4 More dynamic hydrogen bonds are an 11‐atom hydrogen bonded ring Gly3 NH · O‐C Gly5, a 7‐atom hydrogen bonded ring (a γ‐turn) Gly3 C‐O … HN · Gly5 and a 23‐atom hydrogen bonded ring Val61NH … O‐C Val6(l+l).This set of hydrogen bonds results in a right‐handed β‐spiral structure with slightly more than two repeats (approximately 2.2) per turn of spiral. The β‐spiral structure is briefly discussed relative to data on the elastic fiber.
CONFORMATIONAL STUDIES ON SEQUENTIAL POLYPEPTIDES. PART VI. STRUCTURAL INVESTIGATIONS ON (Pro‐Leu‐Gly)10, (Pro‐Leu‐Gly)n AND (Leu‐Pro‐Gly)n
Authors: Scatturin A. , Tamburro A. M. , del Pra A. , Bordignon E. 
Published: August 2010

The conformational properties of (Pro‐Leu‐Gly)10, (Pro‐Leu‐Gly)n and (Leu‐Pro‐Gly)n were investigated both in solution and in solid state. By circular dichroism studies it was possible to demonstrate the formation of an ordered collagen‐like structure for (Pro‐Leu‐Gly)n in hexafluoroisopropanol–water mixtures and in ethylene glycol; (Leu‐Pro‐Gly)n assumes an ordered conformation only in ethylene glycol; (Pro‐Leu‐Gly)10 is unordered under all the conditions studied.X‐ray diffraction patterns indicated that (Pro‐Leu‐Gly)n and (Leu‐Pro‐Gly)n assume a triple helical structure in solid state. In addition, the investigation of (Pro‐Leu‐Gly)n strongly suggests that this type of structure is a single chain triple helix. The X‐ray patterns of (Pro‐Leu‐Gly)10 do not allow us to ascertain a collagen or polyproline II‐like structure for this decatripeptide.
CHEMICAL STUDY OF THE TOPOGRAPHY OF PORCINE LUTROPIN (LH)* USING DINITROFLUOROBENZENE AND DANSYL CHLORIDE
Authors: Combarnous Yves , Hennen Georges 
Published: August 2010

Treatment of porcine lutropin β‐subunit by increasing amounts of dansyl chloride shows that only one fluorescent group can be bound to the free subunit, namely on tyrosine β‐37. This modification prevents reassociation with native α‐subunit.In contrast to dansyl chloride, dinitrofluorobenzene reacts preferentially with tyrosine β‐59. This substitution does not interfere with the reassociation with the native α‐subunit.By using equimolar ratio of dansyl chloride and porcine lutropin α‐subunit it is possible to modify this subunit on a single site, which is found to be a tyrosine residue. The monodansylated α‐subunit is still able to recombine with native β‐subunit but its fluorescence is found to be markedly quenched upon binding. In addition, the O‐dansyltyrosyl fluorescence quenching by potassium iodide is more effective on the recombined dimer than on the free α‐subunit.Both reconstituted dimers (native α x dinitrophenylated β and dansylated α x native β) are without biological activity. It is not clear whether the substituted phenolic groups are essential or whether the added groups prevent the αβ dimer from taking the active conformation. This alternative is discussed in the light of recent data from this laboratory and others.
ISOLATION AND CHARACTERIZATION OF A NEW TRYPSIN‐LIKE ENZYME FROM: Tenebrio molitor L. LARVAE
Authors: Levinsky Haim , Birk Yehudith , Applebaum Shalom W. 
Published: August 2010

A trypsin‐like enzyme (TLE) was separated and purified from Tenebrio molitor larval midgut enzyme solution by ion‐exchange chromatography on a DEAE‐cellulose column. The purified enzyme was found to be a homogeneous protein by electrophoresis in polyacrylamide gels and on cellulose acetate strips, by electrofocusing in polyacrylamide gels and by SDS‐polyacrylamide gel electrophoresis. Its molecular weight was estimated to be 18300 by ultracentrifugal analysis and 24300 on SDS‐polyacrylamide gel electrophoresis. It has an isoelectric point 8.0, it contains only four half‐cystine residues per molecule and the NH2‐terminal amino acid is isoleucine. TLE possesses a high degree of specificity towards trypsin synthetic substrates such as N‐α‐benzoyl‐DL‐arginine p‐nitroanilide (BAPNA), p‐tosyl‐L‐arginine methyl ester (TAME) and poly‐L‐lysine hydrobromide. The optimal pH for TLE activity was found to be 8.0 and the optimal temperature 50° C. Its Km value when assayed on BAPNA was 0.93mM and on TAME 0.08mM. TLE is stable at neutral pHs and its activity is not affected by Ca2+ and by 0.01 M 1, 4‐dithiothreitol (DTT). It is inactivated by DFP and tosyl‐L‐lysine chloromethylketone (TLCK) and is fully inhibited by the naturally occurring trypsin inhibitors such as trypsin‐and α‐chymotrypsin inhibitor (AA) from soybeans, basic pancreatic trypsin inhibitor (BPTI), chick peas trypsin and chymotrypsin inhibitor (CI) and crystalline soybean trypsin inhibitor (CSBTI), forming with them complexes in a molar ratio of 1:1. The Ki value for AA with BAPNA as substrate is 5.87 10‐7 M and for BPTI 7.92 10‐7M.No common antigenic determinants were noted between TLE and bovine trypsin. This finding together with the relatively low number of ‐S‐S‐ bonds in the TLE molecule indicate that TLE differs in conformation from bovine trypsin.
QUANTITATION OF THE β‐ELIMINATION REACTION AS USED ON GLYCOPROTEINS
Authors: Downs F. , Peterson C. , Murty V. L. N. , Pigman W. 
Published: August 2010

The carbohydrate side chains of mucus‐type glycoproteins are O‐glycosidic bonds between N‐acetylgalactosamine to the hydroxyl groups of serine and threonine in the protein core. The alkaline catalyzed β‐elimination reaction, in the presence of sodium borohydride, is used for determining the number of side chains.The present paper presents a study of the quantitativeness of the alkaline borohydride procedure, using four parameters: the loss of seryl and threonyl residues, the formation of alanine and 2‐aminobutanoic acid; the decrease in N‐acetylhexosamine and the recovery of the amino sugar alcohols. Bovine, ovine and porcine submandibular glycoproteins were studied.Evidence is presented for the existence of N‐acetylglucosamine involvement in O‐glycosidic linkages to serine and threonine.Results for the relative rates of β‐elimination indicate that serine‐linked glycosides are released more rapidly than threonine‐linked glycosides.
PHOTOCHEMICAL EVIDENCE FOR THE PRESENCE OF HISTIDYL RESIDUE IN THE ACTIVE SITE OF ALKALINE MESENTERICOPEPTIDASE
Authors: Shopova Maria , Genov Nicolay 
Published: August 2010

The photosensitized oxidation of alkaline mesentericopeptidase in the presence of methylene blue results in a first‐order rate of inactivation. The loss of enzymatic activity towards casein and N‐acetyl‐L‐tyrosine ethyl ester closely correlates with the destruction of one histidyl residue. A pK value of 6.8 is determined from the sigmoid pH‐dependence of the photoinactivation rate. This suggests the involvement of a normal titrating imidazole group in the active site of mesentericopeptidase. The competitive inhibitor Nα‐benzoyl‐L‐arginine protects the enzyme from photoinactivation. A conclusion is made that the active site histidyl residue is modified.Circular dichroism spectra show no change in the protein conformation during the photodynamic treatment.
REACTION OF BOVINE AND EQUINE GROWTH HORMONES WITH TETRANITROMETHANE
Authors: Daurat‐Larroque Silvia T. , Portuguez Manuel E. Moya , Santomé José A. 
Published: August 2010

Bovine and equine growth hormones were chemically modified with tetranitromethane, at pH 7.4 during 5 h and at pH 8.0 in the presence of 8 M urea during 1 h.a) Both hormones have very similar but not identical reactivities.b) The nitration of the reactive tyrosines and tryptophan residues at pH 7.4 produces no detectable changes in their immunological or somatotrophic activities.c) The nitration of all tyrosine residues in both hormones gives rise to a complete loss of somatographic activity with no alteration of the immunological activity.