Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: C01B12 .4
471,332 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two proteinase inhibitors, C-II and D-II, were isolated from soybeans. C-II was shown to be an inhibitor of bovine trypsin [EC 3.4.21.4], bovine alpha-chymotrypsin [EC 3.4.21.1], and porcine elastase [EC 3.4.21.11], whereas D-II inhibited only trypsin. The complete amino acid sequences of the two inhibitors establishors. On the basis of the specificities of the inhibitors and their homologies with other double-headed inhibitors, the reactive sites of C-II seems to be alanine-22 for elastase and arginine-49 for trypsin (and probably also for chymotrypsin). D-II was quite unique because its both reactive sites are arginine residues and it only inhibits trypsin. It is suggested that D-II might be a primitive form of double-headed inhibitor and that the prototype single-headed inhibitor was a trypsin inhibitor with an arginine residue as the reactive site.
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PMID:The amino acid sequences of two soybean double headed proteinase inhibitors and evolutionary consideration on the legume proteinase inhibitors. 98 18

Activities of hydrolytic enzymes on the surface of monkey kidney, canine kidney, L. FM3A and various tumor cells were determined and compared with those in the cell homogenate. Although aminopeptidase (EC 3.4.11.-) activities were always detected on the surface membrane in mammalian cells, trypsin, chymotrypsin and elastase activities were not detected while slight glycosidase activity was detected in a suspension of cultured cells. The activities of alanine-, leucine-, methionine- and phenylalanine-aminopeptidases were rather high but aminopeptidase A, proline-, valine-, glycyl propline dipeptidyl-and glycyl propyl leucine-tripeptidyl-aminopeptidases showed relatively low activities. Aminopeptidase activity was also demonstrated in the isolated membrane fractions. The specific activities of enzymes in these membrane fractions were not significantly greater than in cell homogenate so it was concluded that these enzyme activities were rather loosely bound to the cell membrane. Further evidence for the localization of the aminopeptidase activities on the cell surface was obtained by using glass-bead-bound substrate and detecting the release of the terminal residues. When bestatin, a specific inhibitor against aminopeptidase B and leucine aminopeptidase, was included in the assay system for the enzyme activities on the cell surface, the enzymes were commonly inhibited in all types of cells.
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PMID:Aminopeptidase activities on the surface of mammalian cells. 99 Mar 9

In order to investigate how changes in the structures of side-chain aromatic groups of specific substrates influence binding and kinetic specificity in alpha chymotrypsin [EC 3.4.21.1]-catalyzed reactions, a number of nucleus-substituted derivatives of the specific ester substrates were prepared and steady-state kinetic studies were carried out at pH 6.5 and 7.8. Ac-Trp(NCps)-OMe was hydrolyzed more readily at low substrate concentration than Ac-Trp-OMe due to its smaller Km(app) value, suggesting that the bulky 2-nitro-4-carboxyphenylsulfenyl moiety interacts with outer residues rather than with those in the hydrophobic pocket and that this interaction increases the binding specificity. Inhibition experiments using the corresponding carboxylate and analogous inhibitors, however, showed that the carboxy group at the para position of the phenyl nucleus of the substituent sterically hinders association with the active site of alpha-chymotrypsin at pH 7.8 but not at pH 6.5. The kcat values of Ac-Trp(CHO)-0Me, Ac-Tyr(3-NO2)-OMe, and Ac-m-Tyr-OMe were much higher than those of the corresponding specific substrates, indicating that derivatives with a substitute as large as a formyl, nitro or hydroxyl group at the xi-position are stereochemically favorable to the catalytic process. Remarkable increases in Km(app) were also observed. The individual parameters for Ac-Dopa-OMe, however, were comparable to those for Ac-Tyr-OMe.
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PMID:Kinetic study of alpha-chymotrypsin catalysis with regard to the interaction between the specificity-determining site and the aromatic side chain of substrates. 100 68

Nerve growth factor was isolated from the venom of Naja naja atra by ion exchange and gel permeation chromatography and was found to be homogeneous by disc gel electrophoresis. The molecular weight was estimated to be approximately 20,000 by gel filtration and 22,000 by ultracentrifugation. This protein, which showed an isoelectric point of pH 7.02, probably consists of two subunits of equal molecular weight which are held together or interact with each other noncovalently. The biological activity survives treatment by a number of proteolytic enzymes, such as trypsin [EC 3.4.21.4], chymotrypsin [EC 3.4.21.1], and pepsin [EC 3.4.23.1].
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PMID:Isolation and characterization of nerve growth factor from the venom of Naja naja atra. 100 78

A general kinetic method was developed to analyze enzyme-catalyzed systems complicated by the presence of activation or inhibition by substrate. The method was applied to the alpha-chymotrypsin [EC 3.4.21.1]-catalyzed hydrolysis of p-chlorophenyl and p-methoxyphenyl acetates. Deacylation rate constants which were not complicated by substrate activation were obtained. The analysis shows that the abnormal substituent dependence of kcat in the steady state hydrolysis is due not to substrate activation but to inappropriateness of the two-step mechanism or the existence of more than one acetyl-enzyme intermediate.
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PMID:A method for analyzing enzyme kinetics with substrate activation and inhibition and its application to the alpha-chymotrypsin-catalyzed hydrolysis of phenyl acetates. 100 88

Carboxypeptidase B (peptidyl-L-lysine (-L-arginine) hydrolase, EC 3.4.12.3) has been isolated and purified to apparent homogeneity from activated extracts of human pancreas tissue. The purified enzyme has been shown to be a single polypeptide of 34 000 daltons. In this respect the enzyme from pancreatic tissue, designated native human carboxypeptidase B, differs from the two forms present in human pancreatic juice (fractions I and II), both of which are composed of two polypeptides of approximately 24 000 and 9000 daltons. In addition, the three forms of human carboxypeptidase B differ in electrophoretic mobility in polyacrylamide gel electrophoresis and in chromatographic behavior on DEAE-cellulose. Two immunological methods, micro-complement fixation and radioimmunoassay, have shown a high degree of structural similarity between the three forms of human carboxypeptidase B. Micro-complement fixation experiments indicate that the amino acid sequences of the three enzymes differ by less than one percent. In vitro digestion studies have indicated that trypsin alone is sufficient to convert native carboxypeptidase B to carboxypeptidase B II. However, no combination of trypsin, chymotrypsin, and/or elastase was capable of converting native carboxypeptidase B to carboxypeptidase B I in vitro.
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PMID:Human carboxypeptidase B. II. Purification of the enzyme from pancreatic tissue and comparison with the enzymes present in pancreatic secretion. 100 23

A chymotrypsin-like enzyme (EC 3.4.21.-) was purified from granules of human neutrophiles (polymorphonuclear leucocytes). The isolation procedure included differential salt extractions of the granules followed by affinity chromatography on 4-phenylbutylamine-Affi-Gel. This rapid purification method resulted in obtaining pure enzyme in relatively high yield in short time. The purified granulocyte chymotrypsin-like enzyme has a minimum Mr of 22 378, calculated from its amino acid composition. The Mr value obtained by sodium dodecyl sulphate gel electrophoresis was 20 000-23 000. The enzyme did not react with antibodies which are monospecific to granulocyte elastase. The granulocyte chymotrypsin-like enzyme was inactivated by Dip-F and by the chloromethyl ketone derivatives Z-PheCH2Cl and Z-(Gly)2-PheCH2Cl but not by Tos-PheCH2Cl. It therefore appears that the enzyme has serine and histidine side chains in its active site, like pancreatic chymotrypsin. The granulocyte enzyme substrate specificity is similar to that of pac-Tyr-Nan and Ac-Phe-1-ONap. It also has an intrinsic weak hydrolytic activity towards some classical elastase substrates such as Boc-Ala-ONp and Ac-DL-Ala-1-ONap. The granulocyte enzyme is inhibited by human serum and by human alpha1-antitrypsin. Its affinity for alpha1-antitrypsin is weaker than that of granulocyte elastase for the same inhibitor. The enzyme is stable at neutral pH at 37 degrees C, but unstable at pH 3.5 and at elevated temperature.
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PMID:A rapid method for purification of human granulocyte cationic neutral proteases: purification and characterization of human granulocyte chymotrypsin-like enzyme. 108 Oct 3

The ability of elastatinal and chymostatin, protease inhibitors of microbial origin, to inhibit human leucocyte proteases (EC 3.4.-) was studied. Elastatinal and chymostatin are capable of inhibiting the pancreatic enzymes elastase and chymotrypsin, respectively. It was found in these studies, with synthetic substrates, that elastatinal is a much weaker inhibitor of human leucocyte elastase than it is of porcine pancreatic elastase. Elastatinal caused no inhibition of the activity of human leucocyte chymotrypsin-like protease. Chymostatin was found to be a powerful inhibitor of human leucocyte chymotrypsin-like protease. Its affinity to the leucocyte protease was higher than its affinity to bovine pancreatic alpha-chymotrypsin. Chymsotatin had a weak inhibitory effect on the activity of human leucocyte elastase. Studies were also carried out on the ability of chymostatin to inhibit the release of 35SO2-4 from rabbit articular cartilage by human leucocyte chymotrypsin-like protease. Preincubation of the chymostatin with the protease before the latter was added to the 35SO2-4 -labeled cartilage caused inhibition of proteolysis as measured by 35SO2-4 release. Preincubation of chymostatin with 35SO2-4 -labeled cartilage prior to addition of the human chymotrypsin-like protease to the tissue also inhibited 35SO2-4 release. However, in the case of preincubation of cartilage with alpha1 -antitrypsin there was no such inhibition. It therefore appeared that chymostatin, unlike alpha1 -antitrypsin, was capable of penetrating the cartilage matrix and exerting its inhibitory effect upon the human leucocyte chymotrypsin-like protease that was subsequently added to the tissue.
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PMID:The inhibition of human leucocyte elastase and chymotrypsin-like protease by elastatinal and chymostatin. 108 45

DNA-dependent RNA polymerase lacking subunit sigma was digested with matrix-bound chymotrypsin or trypsin in the presence of 0.4 M NaCl in the monomeric form or at low ionic strength in the oligomeric form. Sigma-containing polymerase was digested in the same way. The course of proteolysis was followed by polyacrylamide gel electrophoresis after dissociation of the enzyme with detergent into subunits and the fragments produced by the hydrolysis. The following results were obtained. (a) The large subunits beta and beta' are cleaved with a much higher rate in the monomeric than in the oligomeric polymerase. (b) Both large subunits are hydrolysed with the same rate. (c) Subunit alpha is hydrolysed almost with the same rate in the monomeric and oligomeric form of polymerase. (d) The same was found for subunit sigma. (e) These effects were independent of the substrate specificity of the protease used. (f) Subunit sigma is much more susceptible to chymotrypsin than to trypsin. (g) Subunit sigma protects the large subunits beta and beta' against tryptic cleavage. These results can be explained in terms of a tentative model for the topography of the protomer-protomer interactions in RNA polymerase. According to this model subunits beta and beta' contain two sites for isologous interactions of protomers. One site can be blocked by attachment of subunit sigma. Subunits alpha and sigma do not participate directly in the association.
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PMID:Digestion with matrix-bound proteases as a possible probe for the topography of the DNA-dependent RNA polymerase from Escherichia coli. 109 50

A method was developed for stepwise wynthesis of oligonucleotides of difined wequence using 2'(3')-O-dihydrocinnamoyl-nucleoside 5'-diphosphates as substrates for polynucleotide phosphorylase [ED 2.7.7.8]. Polynucleotide phosphorylase from Thermus thermophilus catalyzed the transfer of one 2'(3')-blocked ADP to the 3'-terminus of the primer trinucleoside diphosphate, ApApA. The product was 2'(3')-substituted triadenylyladenosine. The blocking group, dihydrocinnamoyl, could be removed completely from the product without destruction of the phosphodiester bond using alpha-chymotrypsin [ED 3.4.21.1] at neutral pH.
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PMID:Novel monofunctional substrates of polynucleotide phosphorylase. The "single-addition" of 2'(3')-O-dihydrocinnamoyl-nucleoside 5'-diphosphate to a primer oligonucleotide. 112 26


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