Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chymotrypsin-type proteinase is detected in the proteolytic system of Asp. oryzae. The action of it and chymotrypsin is shown to depend on formaldehyde. Hydrolysis of substrates, p-nitrophenyl acetate (p-NPA) and N-benzoyl-tyrosine methyl ether (BTME), by both preparations is almost the same. The obtained activity pH-optimum for the studied proteinase esterolytic activity is located in the alkaline zone as well as for crystalline chymotrypsin (substrate p-NPA). It concerns pH of both enzymes stability as well. The enzyme under study is relatively labile. At 50 degrees C there are only traces of the activity in the medium with p-NPG. Its considerable decrease is observed at 40 degrees C. This type activity is more stable on the substrate BTME. 10 min later it disappears completely in the enzymic preparation at a temperature of 60 degrees C at 40 degrees C it is 96.8%. For 24 h at 25 degrees C the activity lowers only by 8%. Crystalline chymotrypsin is stable under these conditions. DEAE-cellulose chromatography (different types of elution) detected multiple forms of proteinase differing in solubility chromatographic properties and specific activity when splitting the substrates p-NPA, BTME and casein.
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PMID:[Properties of chymotrypsin proteinase from Aspergillus oryzae]. 1 30

A rat serum enzyme that catalyzes the conversion of a pro-drug, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11), to an anticancer drug, 7-ethyl-10-hydroxycamptothecin (SN-38), was purified and its properties were characterized. The enzyme was purified by column chromatography on diethylaminoethyl Toyopearl 650M, QAE-Sephadex, Sephadex G-150, Con A-Sepharose and high performance liquid chromatography with an ion-exchanger column. It was most active at pH 7.5 and was stable at pH 4-9 for 1 h at 30 degrees C. The molecular weight was estimated to be 60 and 57 kDa by gel filtration and sodium dodecylsulfate-polyacrylamide gel electrophoresis methods, respectively, and the isoelectric point was 4.6, as determined by isoelectric focusing. The Km value for CPT-11 was 0.28 microM. This enzyme was inhibited by diisopropyl phosphorofluoridate (DFP) and phenylmethanesulfonyl fluoride (PMSF) but insensitive to eserine, p-chloromercuribenzoate (PCMB) and ethylenediaminetetraacetate (EDTA). The enzyme also hydrolyzed p-nitrophenylacetate (p-NPA), a commonly used substrate for esterases, but was not active toward acetylcholine, suggesting that the enzyme is a carboxylesterase[EC 3.1.1.1]. During the hydrolyses of CPT-11 and p-NPA, an initial burst phenomenon similar to that found in the alpha-chymotrypsin-catalyzed hydrolysis of p-NPA was observed. Kinetic analysis revealed that the deacylation of the enzyme is the rate-limiting step in substrate hydrolysis. This enzyme was found to also split other ester derivatives of SN-38 besides CPT-11.
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PMID:CPT-11 converting enzyme from rat serum: purification and some properties. 178 80

Rat striatal membranes from different subcellular fractions were treated with various proteolytic and other enzymes and the binding of a dopamine agonist ([3H]NPA) and of an antagonist ([3H]haloperidol) was assayed in several conditions. In membranes of striatal microsomal and mitochondrial fractions, stereospecific binding of both [3H]NPA and [3H]haloperidol assayed in a monovalent ion-poor buffer was potently and rapidly inhibited by trypsin and certain related proteases. The enzymes did not affect the binding of the ligands when assayed in a buffer containing monovalent ions (greater than or equal to 40 mM NaCl or KCl or a physiological mixture of electrolytes). The inhibition, seen in the monovalent ion-poor buffer, was dependent on the enzyme concentration. The endoproteases (trypsin, alpha-chymotrypsin, papain, ficin) showed nanomolar IC50-values for inhibition of both [3H]NPA and [3H]haloperidol binding. The inhibition occurred very rapidly at 0 degree and was different from the slow proteolytic inactivation seen by prolonged incubation at 37 degrees. It was demonstrated that monovalent ions did not themselves interfere with the interaction between the proteases and the membranes. The observations provide evidence for two different types of stereospecific dopaminergic binding sites which are differentially exposed for ligand binding depending on the concentration of monovalent ions. There sites are protease-sensitive sites, labelled in monovalent ion-poor media and protease-insensitive sites, labelled in media with higher concentrations of monovalent ions. Both types of binding sites bind dopamine agonists and dopamine antagonists with high affinity, but some differences were noted in the binding properties and the drug binding selectivity of the sites. It is argued that both sites form part of the same dopamine receptor macromolecular complex. The findings corroborate the hypothesis that dopamine receptors are composed of different sub-unit binding sites, but these are not distinct agonist and antagonist specific sites. The mechanism by which the protease-sensitive sites are rapidly inactivated by particular proteases, is probably a complexation between the enzymes and certain essential peptide moieties of the receptor sites involved.
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PMID:Effects of proteolytic enzymes and monovalent ions demonstrate protease-sensitive and protease-insensitive stereospecific binding sites on dopaminergic receptors in rat striatum. 704 54