bluuebunny/crossref_metadata_2025_split huggingface dataset:
ISOLATION OF A TRYPSIN‐LIKE ENZYME FROM. STREPTOMYCES PAROMOMYCINUS (PAROMOTRYPSIN) BY AFFINITY ADSORPTION THROUGH KUNITZ INHIBITOR‐SEPHAROSE
Authors: Chauvet Jacqueline , Dostal Jean‐Pierre , Acher Roger 
Published: August 2010

A trypsin‐like enzyme has been isolated from the filtrate of a Streptomyces rimosus forma paromomycinus culture. Purification involves acetone fractionated precipitation, ultrafiltration on a Diaflo UM 10 membrane and affinity adsorption on to Kunitz pancreatic trypsin inhibitor linked to Sepharose. The trypsin‐like enzyme (paromotrypsin) appears homogeneous by zone electrophoresis on gelatinized cellulose acetate. Specific activity toward Tos‐Arg‐OMe, calculated from amino acid analysis, is about 220 u mg‐1. The overall yield in activity is about 30%.The molecular weight of the trypsin‐like enzyme, determined by gel filtration, is around 22,000–25,000 daltons. Electrophoretic migration on cellulose acetate strips indicates an isoelectric point around 8. Amino acid composition has been determined; the protein comprises about 210 residues on the basis of a single histidine residue per molecule.Paromotrypsin is unstable in acidic medium and is not stabilized by calcium ions. Enzymic activity towards Bz‐Arg‐OEt is not increased by the addition of calcium ion in contrast to the activating effect observed on bovine trypsin.Paromotrypsin is inhibited by TLCK and NPGB; it interacts with naturally occurring bovine trypsin inhibitors such as soya bean and Kunitz pancreatic inhibitors, but not with chicken ovomucoid. Proteolytic specificity, examined by hydrolysis of oxidized Kunitz pancreatic inhibitor and characterization of resulting peptides, seems similar to that of bovine trypsin.
RELATIVE REACTIVITIES OF SULFHYDRYL GROUPS WITH N‐ACETYL DEHYDROALANINE AND N‐ACETYL DEHYDROALANINE METHYL ESTER
Authors: Snow John T. , Finley John W. , Friedman Mendel 
Published: August 2010

The reaction rates in aqueous solutions of aminothiols, thiols, and other compounds with N‐acetyl dehydroalanine and its methyl ester (2‐acetamidoacrylic acid and methyl 2‐acetamidoacrylate) were studied as a function of the structure of the thiol compound in aqueous solutions. Correction of the observed second‐order rate constants to identical thiol anion concentration gave a series of computed rate constants whose logarithms showed a linear dependence on the pK's of the thiol group in similar steric environments.Comparison of the addition rates of penicillamine to N‐acetyl dehydroalanine and its methyl ester showed the methyl ester to react approximately 11,400 times faster than the acid. Addition rates for thiol acids and aromatic and heterocyclic thiols were also compared; each showed sluggish reactivity with dehydroalanine, but each reacted readily with methyl dehydroalanine. The kinetic data were applied in developing a method for preparing lanthionine in high yield.
THE EFFECT OF CALCIUM CHLORIDE ON THE ACTIVITY AND INHIBITION OF BACTERIAL COLLAGENASE
Authors: Head David L. , Yankeelov John A. 
Published: August 2010

The enzymatic behavior and inhibition patterns of collagenase of Clostridium histolyticum in the presence of 0.5 M and 3.4 mM CaCl2 have been examined viscosimetrically. The more concentrated salt was found to enhance the rate of digestion of calfskin collagen when either measured viscosimetrically or colorimetrically by trinitrobenzenesulfonate. However, the rate of digestion of calfskin gelatin is unaffected by 0.5 M CaCl2 as determined colorimetrically.Calcium chloride also proved to have a marked effect on the inhibitory behavior of a series of imidazole compounds. Histidine (10 mM) is about three‐fold more effective as an inhibitor in 0.5 M CaCl2 than in 3.4 mM CaCl2, whereas a reverse effect is true for histamine. Imidazolylpropionate (10 mM) was only weakly inhibitory (16%) in 0.5 M CaCl2 and not at all in 3.4 mM CaCl2. Inhibition by 10 mM imidazole was not detectable. These observations may be useful in the design of inhibitors for tissue collagenases which share a number of common characteristics with the bacterial enzyme.
UNUSUAL BEHAVIOUR OF A PROTEIN: REVERSIBLE QUANTITATIVE PRECIPITATION OF STAPHYLOCOCCAL DELTA‐HAEMOLYSIN BY LOW CONCENTRATIONS OF SOME ORGANIC SOLVENTS
Authors: Heatley N. G. 
Published: August 2010

Staphylococcal delta‐haemolysin is precipitated from watery solutions by low concentrations of chloroform. The effect on this precipitation of pH, kind and concentration of salts, and concentration of, and time of exposure to, chloroform have been investigated. Some but not all of the other solvents tested cause a similar precipitation. The haemolytic activity is not destroyed and under appropriate conditions precipitation is quantitative.The dry lysin will take up nearly double its weight of chloroform when exposed to the vapour. Some is bound strongly.
THE PRIMARY STRUCTURE OF MUSKRAT PANCREATIC RIBONUCLEASE
Authors: van Dijk Henk , Sloots Boele , van den Berg Annelies , Gaastra Wim , Beintema Jaap J. 
Published: August 2010

Pancreatic ribonuclease from muskrat (Ondatra zibethica) was isolated and its amino acid sequence was determined from tryptic digests of the performic acid‐oxidized and the reduced and aminoethylated enzyme. The peptides have been positioned in the sequence by homology with other ribonucleases. This could be done unambiguously for all peptides except Arg‐Arg (tentative position 32–33) and Ser‐Arg (tentative position 75–76). The amino acid sequences of the peptides were determined by the dansyl‐Edman method, with the exception of residues 23–25 and 99–102, which were positioned by homology.The enzyme differs in 38 positions from the enzyme from rat and in 31–42 positions from other mammalian pancreatic ribonucleases, while rat ribonuclease differs at 44–52 positions from the other enzymes. These data point to a common ancestry of the enzymes from muskrat and rat and an increased evolution rate of rat ribonuclease after divergence of the ancestors of both species.Muskrat ribonuclease contains no carbohydrate, although the enzyme possesses a recognition site for carbohydrate attachment in the sequence Asn‐ Val‐Thr (62–64).
STRUCTURE‐ACTIVITY STUDIES ON MAMMALIAN TISSUE LYTIC ENZYMES: CHEMICAL CHARACTERIZATION AND SUBSTRATE SPECIFICITY OF RAT KIDNEY NUCLEAR LYSOZYME*
Authors: Raghunathan R. , Shantoo Gurnani 
Published: August 2010

Studies on the structure and substrate specificity of purified rat kidney nuclear (RKN) lysozyme are reported.The carboxyl and amino terminal residues of RKN‐lysozyme were found to be leucine and alanine respectively. The amino acid composition indicated similarities and differences as compared with that of hen egg white (HEW) lysozyme. There were alterations in the nine amino acid residues, Lys, His, Arg, Asp, Glu, Pro, 1/2 Cys, Tyr and Trp. The other nine residues were present in identical proportions to those of HEW‐lysozyme. The decrease in the arginine and aspartic acid residues was found to be compensated by the increase in the number of lysine, histidine and glutamic acid residues. The overall ratio of the acidic to basic amino acids has thus been conserved in the mammalian enzyme. In addition, RKN‐lysozyme contained decreased numbers of Trp, Tyr and 1/2 Cys, and increased numbers of proline residues as found in HEW‐lysozyme. RKN‐lysozyme did not cross react with heterologous antibodies produced against HEW‐lysozyme, and vice versa.RKN‐lysozyme showed distinct specificity towards the lysis of M. luteus. Against this substrate, it was three times more efficient than HEW‐lysozyme. It also cleaved E. coli B, but its efficiency was half as much as with M. luteus. However, it cleaved P. septica and B. subtilis at a rate similar to HEW‐lysozyme under identical conditions.
THE RECONSTRUCTION OF A FRAGMENT OF PRIMORDIAL GENETIC INFORMATION FROM MODERN PROTEINS: PGI‐F1 (AHAP)
Authors: Bauer Klausdieter 
Published: August 2010

In a continuation of earlier studies the connection between a reconstructed ancestral histone IV peptide and various sequences from non‐histone proteins was investigated. This peptide, AHAP, was found to be related to partial peptides from the human encephalitogenic protein, immunoglobulin L‐chains, fibrinopeptide A, glyceraldehyde‐3‐phosphate‐dehydrogenase, TMV coat protein and several other proteins and protein families; for comparison, nodal sequences were employed wherever possible.The widespread occurrence of genetic information expressed in AHAP caused us to rename the peptide PGI‐F1 (primordial genetic information‐fragment 1) since this peptide is apparently part of a very primitive and ancient genetic information, and may be called “protogene”.
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.
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.
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.
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.
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.
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.
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.