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)

When the competitive inhibitor benzeneboronic acid (BBA) forms a complex with alpha-chymotrypsin [EC 3.4.21.1] protons are released in the acidic pH region. The proton release can be measured by a difference potentiometric technique. The proton release is also observed in chymotrypsinogen A but not in TRCK-, DIP-, and anhydrochymotrypsins. Based on these observations, a simple procedure to estimate the equilibrium constants of the trigonal-tetrahedral interconversion of BBA is proposed. Thermodynamic parameters of the ionization of His 57 and of each step involved in BBA binding can be estimated from the temperature dependence of the proton release. Those of His 57 are essentially the same as those of imidazole in water. Regarding the interconversion of BBA on the enzyme, the value of delta S is similar to delta S not equal to of the deacylation step of nonspecific substrates, and delta H is remarkably reduced from that for the ionization of BBA in water. The enthalpic gain of enzymic process is suggested to be due to the change of the proton acceptor, which is water in the case of the ionization of BBA in water, to imidazole on the enzyme.
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PMID:Potentiometric studies on benzeneboronic acid-alpha-chymotrypsin interactions. 0 50

The interactions of porcine alpha2-macroglobulin (alpha2M) with native proteinases, their zymogens and the chemically-modified enzymes were compared. The alpha2M did not bind to chymotrypsinogen, or to most of the chemically modified derivatives of alpha-chymotrypsin, trypsinogen, DIP- and PMS-trypsins, but it could interact with anhydrotrypsin, PMS-subtilisin, and O-acetylated neutral subtilopeptidase. Anhydrotrypsin appeared to bind very tightly to alpha2M, as does native trypsin, whereas the binding of PMS-subtilisin to alpha2M was weaker than that of the native enzyme, judging from exchange experiments with labeled enzyme and from competitive enzyme assay. There are, however, some differences in the mode of interaction with alpha2M between native and anhydrotrypsins. (1) The shape and the magnitude of ultraviolet difference spectra caused by the interaction with alpha2M were significantly different. (2) The interaction of alpha2M with active proteinase led to the formation of new amino-terminal amino acids, while that with anhydrotrypsin did not. (3) In vivo experiments showed that radioactivity of 3H-labeled trypsin-alpha2M complex was rapidly cleared from the plasma of rats, whereas the anhydrotrypsin-alpah2M complex was cleared very slowly. These results suggest that the proteolytic activity of the enzyme is not obligatory for the first phase of alpha2M-proteinase interaction (formation of Michaelis-type complex), but only the proteolytically modified complex is cleared rapidly from the blood circulation system.
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PMID:Interaction of porcine alpha2-macroglobulin with chemically modified proteinases. 65

The statistical availability of tryptophan and tyrosine residues with one ring face fully exposed to solvent was examined for two serine proteases and their derivatives by investigating the formation of charge transfer (CT) complexes between the aromatic donor residues of the protein and the acceptor 1-methylnicotinamide chloride. The availability of the ring face of one of the two exposed tryptophan residues in trypsin has been previously shown to be pH dependent and to parallel the acid side of the pH-activity profile of the enzyme. The present results indicate that, in diisopropylphosphoryl-trypsin (DIP-trypsin), this residue [which was identified as Trp-215 in native trypsin (chymotrypsin numbering)] is locked in a relatively rigid, pH-independent conformation with one ring face rotated out toward the solvent. In the zymogen and DIP-zymogen, the ring face is essentially unavailable. Chymotrypsin, like trypsin, has a pH-depent tryptophan residue available for complexation with the CT acceptor, but unlike trypsin, the pH dependence is apparently associated with dimerization of the enzyme. These and other data suggest this residue is the same as in the homologous trypsin structure, i.e., Trp 215, and that the ring face is mostly buried in the zymogen. Comparison of the crystal structure models of chymotrypsin and chymotrypsinogen shows that, as the specificity pocket opens up from its collapsed structure upon zymogen activation, the ring face of Trp-215 moves out and rotates relative to the surface of the enzyme in such a fashion as to become more accessible to solvent. These observations are in accord with the present CT results and provide additional support for the assignment of changes in Trp-215 availability to parallel changes in the conformation of the specificity pocket of these serine proteases. The present investigation also shows that, although a tryptophan ring face is partly exposed in DIP-chymotrypsin, its statistical availability more closely resembles that of the zymogen than the native enzyme. The reverse appears to be true for DIP-trypsin, which suggests the possibility that the specificity pocket in DIP-chymotrypsin may be partially collapsed while the catalytic residues are frozen in the conformation of the acyl-enzyme.
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PMID:Flexibility in the specificity site of serine proteases. 94 68

The partial amino acid sequence of porcine elastase II, isolated from crude trypsin Type II, was determined. The enzyme consists of two polypeptide chains, a light chain composed of 11 residues, and a heavy chain (Mr = 23 500) with four intrachain disulfide bridges; the two chains are held together by one interchain disulfide bond. Elastase II was fragmented into several peptides by chemical cleavages with CNBr at the two methionine residues, 99 and 180 (chymotrypsinogen numbering), and with hydroxylamine at the peptide bond following DIP-Ser195. About 50% of the sequence was determined and the positions of 120 amino acids were located, including the light chain residues and most of the active site residues. The partial sequence shows 64% difference between porcine elastase II and elastase I and only 26% difference between porcine elastase II and bovine chymotrypsin B.
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PMID:Partial amino acid sequence of porcine elastase II. Active site and the activation peptide regions. 363 56

The behavior of Listeria monocytogenes (Scott A) on fully processed Italian Mozzarella cheese was examined in presence and in absence of bacteriocins produced by Lactococcus lactis ssp. lactis strains (DIP 15 and DIP 16). These strains, isolated from raw milk, produced heat stable bacteriocins that were inactivated by pronase, alpha- chymotrypsin and proteinase K, but not by pepsin, trypsin and catalase. The addition of crude bacteriocins to the growing culture of Listeria monocytogenes resulted in a significant reduction in cell number at 5 degrees C, but not at 30 degrees C. Mozzarella cheese was inoculated with the Listeria culture to obtain an initial level of approximately 30 CFU/cm2 surface of Mozzarella and approximately 10(3) CFU/ml of the surrounding fluid and then packaged in bags containing the heat-treated neutralized-cultures of Lactococcus lactis ssp. lactis in skim milk (in Italy, Mozzarella is sold in small size pieces, individually packaged in bags containing some fluid). Bags were stored at 5 degrees C up to 21 days. The presence of bacteriocins resulted in apparent death of Listeria monocytogenes after 24 h storage. After 7 days of storage, a revival of Listeria monocytogenes was observed, followed by an increase in number. However, for a storage period of 2-3 weeks the number of Listeria monocytogenes remained significantly below the number observed for Mozzarella cheese packaged in absence of the heat-treated cultures of Lactococcus lactis.
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PMID:Behavior of Listeria monocytogenes in Mozzarella cheese in presence of Lactococcus lactis. 765 15