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

---

Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A chymotrypsin-like esterase was purified from beef lung. This lysosomal enzyme, not previously characterized, seemed to be composed of two or more forms with molecular weights of about 52 000. It hydrolysed N-benzoyl-DL-phenylalanine beta-naphthol ester at acid and neutral pH; it polymerized L-phenylalanine methyl ester(Phe-OMe) at neutral pH; and it transferred the Phe-residue from Phe-OMe to hydroxylamine at neutral pH. Phenylmethanesulfonyl fluoride, an inhibitor of hydrolytic enzymes with serine in their catalytic site, inhibited this enzyme, but pepstatin, the cathepsin D (EC 3.4.4.23) inhibitor, did not. Sulfhydryl reagents were not required for activity. Macrophages, especially pulmonary alveolar macrophages, were a rich source of this esterase, so it is likely that the enzyme purified from lung came from its macrophages. The esterase hydrolysed and transferred monoamino acid esters, especially those of the aromatic type. Cathepsin C, the dipeptidyl peptide hydrolase (EC 3.4.14.1), acted only on dipeptide esters and amides. Pancreatic chymotrypsin acted on both monoamino acid and dipeptide esters. The chymotrypsin-like esterase did not hydrolyse hemoglobin, casein, or plasma albumin. Thus its proteolytic activity, if present, must be limited to specific substrates, as yet unknown.
...
PMID:Macrophage esterase: identification, purification and properties of a chymotrypsin-like esterase from lung that hydrolyses and transfers nonpolar amino acid esters. 24 Apr 26

Mono[14C]acetyl-chymotrypsin was prepared by treating alpha-chymotrypsin with a 10-fold molar excess of p-nitrophenyl[14C]acetate at pH 5, and the acetylated enzyme was isolated free of excess reagents by gel filtration. Deacetylation at pH 6.0 was followed by observing the decrease in acid-precipitable radioactivity and provided a first-order rate constant of 0.02 +/- 0.008 min-1. Reactivation of the acetylated protein was followed by continuously monitoring the appearance of esterolytic activity towards alpha-N-acetyltyrosine ethyl ester. Reactivation at pH 6.0 occurred exponentially with a first-order rate constant of 0.2 +/- 0.015 min-1, the reactivated enzyme exhibiting an apparent catalytic contant (k' cat) of 1200 +/- 60 min-1, which decreased to a value of 945 +/- 15 min-1 by an apparent first-order process with a rate constant of 0.025 +/- 0.006 min-1. These results are interpreted in terms of a two-step deacetylation of monoacetyl-chymotrypsin involving an acetylated intermediate with esterase activity.
...
PMID:Kinetic evidence for an intermediate in the deacetylation of monoacetyl-chymotrypsin. 26 16

Several human granulocyte proteinases sensitive to the thermo- and acid-resistant proteinase inhibitor from rabbit serum (TASPI) were revealed, using TASPI-Sepharose 4B. It was found that TASPI inhibits the following human granulocyte proteinases: granules-localized kininogenase and chymotrypsin-like kininase (serine proteinases), elastase-like proteinase and benzoyl arginine ethyl ester esterase, as well as chymotrypsin-like kininase from the post-granule supernatant. These enzymes were compared to known granulocyte proteinases. Some carboxylic kininogenase sensitive to TASPI was identified in the granulocyte membrane debris fraction. The capability to inhibit neutral kininogenase suggests that TASPI is a first natural proteinase inhibitor, which can differentiate granulocyte and blood plasma kininogenases. Using trypsin-Sepharose 4B in the granulocyte post-granule supernatant, the acid-resistant trypsin and chymotrypsin inhibitor was identified. The data obtained are indicative of an antiinflammatory function of TASPI in mammals.
...
PMID:[Inhibition of human granulocyte proteinases by a heat and acid-stable proteinase inhibitor from rabbit serum]. 43 77

Neutral proteoglycanase and other protease activity from cellular and CM fractions of monolayer-cultured rabbit articular chondrocytes were studied. The cellular fraction comprising soluble cytoplasmic enzymes possessed concentration-dependent elastase-like esterase activity and activity against trypsin and chymotrypsin synthetic substrates but had little caseinase activity. The 20% ammonium sulfate precipitate of CM possessed more neutral caseinase activity than the 60% ammonium sulfate precipitate and the bulk of activity against the synthetic substrates. Activity against bovine nasal septum PG was present in these fractions. Both the 20% and 60% ammonium sulfate fractions reduced the viscosity and the S of the PG substrate. This activity was incompletely inhibited by preincubation with either 5 mM o-phenanthroline or 10 mM EDTA, indicating that it was paritally metal-dependent. The activity in the cellular fraction was also partially inhibited by o-phenanthroline but more so by EDTA. These data indicate that chondrocytes synthesize and secrete into the culture medium neutral proteoglycanase(s) capable of initiating degradation of PG derived from the neutral pH cartilage matrix. The inhibitory profiles, together with recent evidence of enzymes with similar activity extracted from cartilage suggested that the proteoglycanase enzyme(s) may occur in multiple forms.
...
PMID:Metal-dependent neutral proteoglycanase activity from monolayer-cultured lapine articular chondrocytes. 43 3

Coupling of bovine carboxypeptidase A with diazotized 5-amino-1H-tetrazole increases esterase activity, decreases peptidase activity slightly, and modifies one tyrosyl residue. Subsequent nitration of the azoenzyme has no further effect on esterase activity, decreases peptidase activity markedly, and modifies a second tyrosyl residue. Analysis of the azopeptides isolated from a chymotrypsin digest of the doubly modified enzyme by affinity, ion exchange, and high pressure liquid chromatography indicates that the principal residue modified by diazo-1H-tetrazole is Tyr-248. Analysis of the nitropeptides isolated by similar procedures indicates that nitration occurs mainly at Tyr-198. This residue becomes susceptible to modification only as a consequence of a conformational change that accompanies azo coupling of Tyr-248. These results describe a unique example of the influence of protein structure on the reactivity of functional amino acid residues and illustrate an important aspect of chemical modification of enzymes.
...
PMID:Functional tyrosyl residues of carboxypeptidase A. The effect of protein structure on the reactivity of tyrosine-198. 56 10

The syntheses are described of p-guanidino-L-phenylalanine and some of its derivatives. alpha-N-(p-Toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester is an excellent substrate of bovine trypsin (EC 3.4.21.4) (Km 57 micron; kcat. 320s-1 at pH 7.4-8.0) and a very poor substrate of human thrombin (EC 3.4.21.5) (Km 190 micron, kcat. 0.2s-1) and bovine chymotrypsin (EC 3.4.21.1). The ester inhibits thrombin clotting activity. It also inhibits the amidase and esterase activities of human thrombin, this inhibition being of the mixed type. The inhibition constant, K1, of the order of 1 micron, increases with increasing inhibitor concentration. This suggests that the enzyme binds the inhibitor at multiple sites. The importance of the residue at the P1 position [notation of Berger & Schechter (1970) Philos. Trans. R. Soc. London Ser. B 257, 249-264] in determining the selectivity of a substrate or quasi-substrate among trypsin-like enzymes is borne out. p-Guanidino-L-phenylalanine may have a use in the synthesis of selective peptide inhibitors of thrombin.
...
PMID:The interaction of alpha-N-(p-toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester with thrombin and trypsin. 62 42

At 20 degrees C, aflatoxin B1, at a sublethal dose, decreases the activity of alkaline phosphatase (EC 3.1.3.1), alpha-glucosidase (EC 3.2.1.20), esterase (EC 3.1.1.1), chymotrypsin (EC 3.4.21.1), leucine aminopeptidase (EC 3.4.11.1), and phosphoamidase (EC 3.9.1.1) biosynthesis in Bacillus thuringiensis (Berliner). In contrast, at 41 degrees C no significant decrease was observed. At this temperature, the mycotoxin is not destroyed or metabolized and bacterial cells are resistant to the toxin.
...
PMID:[Effect of aflatoxin B1 on the enzymatic activities of Bacillus thuringiensis (Berliner)]. 88 28

Isolation of tropoelastin is complicated by the presence of a neutral protease closely associated with tropoelastin that is capable of sequentially degrading tropoelastin to small peptides. Substrate and inhibitor specificities of this neutral protease associated with purified tropoelastin were examined. The enzyme displayed proteolytic activity against casein, and esterase activity was detected when assayed against N-tosyl-L-arginine methyl ester but not against tert-butyl-oxycarbonyl-L-alanine p-nitrophenyl ester. No appreciable elastinolytic activity was detectable against either insoluble sodium dodecyl sulfate treated elastin or maleylated tropoelastin. The enzyme was not inhibited by the chymotrypsin inhibitor toluenesulfonylphenylalanine chloromethyl ketone. The enzyme was inhibited by phenylmethanesulfonyl fluoride and, to various degrees, by metal chelators. Tosyllysyl chloromethyl ketone, epsilon-aminocaproic acid, and Aprotinin (pancreatic trypsin inhibitor--Kunitz type), all inhibitors of trypsin-like enzymes, were very effective inhibitors, as were soybean trypsin inhibitor and human alpha-1-antitrypsin. The data suggest that the tropoelastin-associated enzyme is a neutral serine protease with trypsin-like specificity.
...
PMID:Trypsin-like neutral protease associated with soluble elastin. 90 57

A search for the source of the residual esterase activity of crude lima bean protease inhibitor-binding anhydrochymotrypsin preparations was undertaken. The preparations were found to contain about 40% of protein that possesses 1% (kc/Km) to 12% (kc) of the esterase activity of alpha-chymotrypsin. The active protein was isolated by affinity chromatography on soybean trypsin inhibitor-Sepharose. It appears to be an anhydroenzyme or a mixture of a limited number of anhydroenzymes in which a serine other than the catalytically essential serine-195 of the native enzyme has been converted to dehydroalanine.
...
PMID:Residual esterase activity of lima bean inhibitor-binding anhydrochymotrypsin preparations. 92 2

Nitration of bovine carboxypeptidase A crystals with tetranitromethane increases esterase activity, decreases peptidase activity, and modifies about one tyrosyl residue. Modification of enzyme crystals avoids the polymerization that occurs when the enzyme is nitrated in solution. Two procedures have been employed to identify the tyrosyl residues nitrated. The first involves cyanogen bromide cleavage and isolation of the fragment containing residues 104-301. After solubilization by succinylation, this fragment is digested with chymotrypsin, the peptides are fractionated by gel filtration, and the nitrotyrosyl peptides are purified by affinity chromatography on an antinitrotyrosyl antibody-Sepharose conjugate followed by ion-exchange chromatography. In the second, the nitroenzyme is heat denatured, digested by chymotrypsin, and fractionated on the affinity and ion-exchange columns. By both methods, the major mitropeptides, representing between 60 and 80% of the nitrotyrosyl label, are uniquely compatible with that segment of the sequence of carboxypeptidase containing Tyr-248. A nearby cation, either the active site zinc ion or Arg-145, would seem to be an important factor in determining the selective nitration of this residue.
...
PMID:Chemical modification of carboxypeptidase A crystals. Nitration of tyrosine-248. 94 53


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---