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

PST (E.C. 2.8.2.1) plays an important role in the metabolism of many drugs, catecholamine metabolites, and catecholamines. PST activity was detected in each of 178 human RBC lysates. When MHPG was used as a substrate, the activity ranged from 28 to 1385 U/ml of RBC, with an average value of 217.7 +/- 13.1 (mean +/- S.E.M.). However, there was not a direct relationship between quantity of RBC lysate and enzyme activity, an observation that raised the possibility of endogenous enzyme inhibitors. Therefore human RBC PST was partially purified (415-fold) to use in the study of tissue enzyme inhibitors. The pH optimum of the partially purified enzyme was 7.5, with an apparent Km value for [35S]PAPS of 0.46 microM and an apparent Km value for MHPG of 260 microM. When the partially purified enzyme was added to each of 20 human RBC lysates, its activity was inhibited an average of 91% +/- 0.6 (mean +/- S.E.M.). Endogenous inhibitors were also present in homogenates of human renal cortex and in homogenates of a variety of rat tissues. RBC lysates contained at least two PST inhibitors: a low-molecular-weight inhibitor (less than 2000) that was heat-, acid-, and base-stable, dialyzable, and resistant to digestion by chymotrypsin; and a high-molecular-weight inhibitor (greater than 65,000) that was heat-labile and nondialyzable. Whether the RBC enzyme activity may serve as an indicator of PST activity in less accessible tissues remains to be determined. However, the first step toward testing this hypothesis will require the accurate measurement of PST activity in tissue preparations by a procedure that removes or inactivates enzyme inhibitors.
 ...
PMID:Phenolsulphotransferase: enzyme activity and endogenous inhibitors in the human erythrocyte. 46 73

Benzoyl- and isopentenoyl phosphoric triamides (BPA and IPA) strongly inhibited urease activities from jack bean, soybean, watermelon seed, Proteus mirabilis, P. rettgeri, P. vulgaris, Mycobacterium smegmatis, and Ureaplasma urealyticum. Their I50 values (the final concentration causing 50% inhibition), independent of enzyme source, were 2-21 nM, which are about 1,000-fold lower than that of caprylohydroxamic acid, one of the most potent urease inhibitors. ATP-urea amidolyase activity was inhibited 50% by BPA at a higher concentration of 0.28 mM, but was not affected by IPA even at 1.3 mM. Thirteen kinds of hydrolases (trypsin, chymotrypsin, thermolysin, leucine aminopeptidase, papain, lipase, alpha-amylase, glucuronidase, asparaginase, arylsulfatase, alkaline phosphatase, acid phosphatase, and true cholinesterase), two oxidoreductases (catalase and alcohol dehydrogenase), three transferases (glutamic-oxaloacetic aminotransferase, gamma-glutamyl transpeptidase, and arylsulfotransferase) and two kinases (pyruvate kinase and creatine kinase) were not affected at all even at 1 mM BPA and IPA. Exceptionally, pseudo-cholinesterase from human serum was inhibited by BPA and IPA, whose I50 values were 70 nM and 10 muM, respectively, using acetylthiocholine as a substrate. These values increased to 0.55 muM and 54 muM, respectively, when acetylcholine was used as a substrate. These results show that N-acylphosphoric triamides potently and specifically inhibit urease activity at concentrations of nM order.
 ...
PMID:Specific inhibition of urease by N-acylphosphoric triamides. 384 42

An organic solvent-stable protease (PST-01 protease) in a culture broth of organic solvent-tolerant Pseudomonas aeruginosa PST-01 was purified by successive hydrophobic interaction chromatography using Butyl-Toyopearl gels. The purified enzyme was homogeneous as determined by SDS-polyacrylamide gel electrophoresis. PST-01 protease had a molecular mass of 38 kDa. The optimum temperature and pH for casein hydrolysis were 55 degrees C and 8.5, respectively. PST-01 protease was stable at pH 8-12 and below 50 degrees C and was determined to be a metalloprotease which was inhibited by EDTA, 1,10-phenanthroline, and phosphoramidon. PST-01 protease inhibited by EDTA was reactivated completely by the addition of zinc or cobalt ions. The stability of PST-01 protease in solutions containing water-soluble organic solvents or alcohols was higher than that in the absence of organic solvent. Furthermore, in general, PST-01 protease was more stable than commercially available proteases, namely, subtilisin Carlsberg, thermolysin, and alpha-chymotrypsin, in the presence of water-soluble organic solvents or alcohols.
 ...
PMID:Purification and characterization of organic solvent-stable protease from organic solvent-tolerant Pseudomonas aeruginosa PST-01. 1623 26

The half-life of the activity of the PST-01 protease that was secreted by organic solvent-tolerant Pseudomonas aeruginosa PST-01 was very long in the presence of methanol as compared to that in the absence of methanol. The conformational transitions of the PST-01 protease, alpha-chymotrypsin, thermolysin, and subtilisin in the presence and absence of methanol were monitored by measuring the CD spectra. The conformational stabilities of the PST-01 protease and subtilisin in the presence of methanol were higher than those in the absence of methanol. This resulted in high stability of these proteases in the presence of methanol. Furthermore, it was suggested that the organic solvent stabilities of enzymes were closely related to the secondary structure by monitoring the conformational transitions of polyamino acids, which form the particular conformations, in the presence and absence of methanol.
 ...
PMID:Stabilities and conformational transitions of various proteases in the presence of an organic solvent. 1726 83