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)

The 15 exposed carboxyl groups of alpha-chymotrypsin were modified with glycine ethyl ester at low pH using barbodiimide reagent. The specificity of the modified enzyme (Chy-15) was studied over the pH range of 4 to 9 with both N-acylated and non-N-acylated amino acid esters. The modified enzyme had lower reactivity toward N-acylated esters than non-N-acylated esters compared to the native enzyme. Typical substances such as acetyl- and benzoyl-L-tyrosine ethyl esters retained 4 and 9% activity, whereas phenylalanine ethyl ester was slightly more reactive with the modified than with the native enzyme. The pH-rate profiles of acetyl-L-phenylalanine ethyl ester and tryptophan ethyl and benzyl esters were investigated in detail. Analysis of these profiles revealed three pKa values of approximately 5, 7, and 9 related to a functional carboxyl, imidazoyl, and an amino group, respectively. Since similar pKa values occur for the native enzyme, modification did not block the carboxyl corresponding to pKa 5. A mechanism is proposed for catalysis which includes both the protonated and unprotonated form of the imidazoyl (His-57) and utilizes water rather than a carboxyl (Asp-102) as the proton sink.
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PMID:Specificity of alpha-chymotrypsin with exposed carboxyl groups blocked. 0 45

Chymotrypsin is specifically adsorbed at low ionic strength and alkaline pH to hydroxyalkyl methacrylate gels with N-benzyloxycarbonylglycl-D-phenylalanine or N-benzyloxycarbonylglycyl-D-leucine attached through 1,6-hexanediamine. Chymotrypsin is not adsorbed either to the unmodified gel (Spheron) or to the gel with attached, 1,6-hexanediamine (NH2-Spheron). The adsorption of chymotrypsin to Z-Gly-D-Phe-NH2-Spheron was investigated as a function of pH and ionic strength. Trypsin is not adsorbed to this gel. Chymotrypsin isolated from a crude pancreatic extract by affinity chromatography on Z-Gly-D-Phe-NH2-Spheron had the same activity as the enzyme isolated on a column of Spheron, to which the naturally-occurring trypsin inhibitor had been coupled.
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PMID:Affinity chromatography on hydroxyalkyl methacrylate gels. III. Adsorption of chymotrypsin to poly(hydroxyalkyl methacrylates) with covalently bound benzyloxycarbonyl-glycyl-D-phenylalanine and -D-leucine as function of pH and ionic strength. 0 31

Steady state kinetic studies of alpha-chymotrypsin [EC 3.4.21.1]-catalyzed hydrolysis of nucleus-substituted derivatives of the specific substrates were made at pH 6.5 and 7.8. Ac-Trp(NCps)-OMe was hydrolyzed more readily than Ac-Trp-OMe owing to its smaller Km value. The kcat values of Ac-Trp(CHO)-OMe and Ac-Tyr(3-no2)-ome were higher than those of the corresponding unmodified substrates, suggesting that derivatives with a substituent as large as a formyl or nitro group at the epsilon-position are stereochemically favorable to the catalytic process. Derivatives of Ac-Phe-OMe with a chain of four atoms at the 3 or 4-position of the phenyl nucleus and 2,3-dihydropyrrolo[2,3-b]indoles derived from Ac-Trp-OMe were not hydrolyzed at all.
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PMID:alpha-Chymotryptic hydrolysis of derivatives of the specific substrates with substituents in the nucleus. 0 6

Three vinyl monomers, M-1, M-3, and M-5, in which L-phenylalanine p-nitroanilide was acylated with CH2==CHCONH(CH2)nCO--(n = 1, 3, 5) were synthesized. They were co-polymerized with a large excess of acrylamide (co-polymers PAm-1, PAm-3, and PAm-5) and with a large excess of acrylic acid (co-polymers PAc=1, PAc-3, and PCc-5). In addition, M-5 was co-polymerized with acrylamide containing 2.8 mol % of the hydrophobic monomer N-acrylyl-1-naphthylamine (co-polymer PAm-5N). The rates of the chymotrypsin-catalyzed hydrolysis of the nitroanilide groups of M-5 and the various co-polymers were determined over a range of pH. For some of the systems data were also obtained over a range of substrate concentrations to derive values for Vmax and Km. Results obtained with PAm-5 were found to be independent of the chain length of the co-polymer. At pH 7, 25 degrees and with 2.7 X 10(-6) M enzyme, Vmax values for M-5, PAm-k, PAm-5N, and PAc-5 were 5.5, 5.5, 10, and 3.6 X 10(-8) M/S, while Km values were 8.5, 16.5, 10, and 2.2 X 10(-5),respectively, With PAc-5, the pH activity profile was shifted to higher acidities as compared to the profiles obtained with M-5 and PAm-5. The susceptibility of the co-polymers to chymotrypsin attack decreases sharply with a decreasing spacing of the L-phenylalanine p-nitroanilide residue from the backbone of the polymer chains.
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PMID:Enzymatic attack on side chains of synthetic polymers. Chymotrypsin-catalyzed hydrolysis of specific substrate groups attached to acrylamide or acrylic acid co-polymers. 0 40

1. The specificity of cathepsin G, a neutral proteinase from human spleen, was examined by use of low-molecular-weight substrates. The enzyme was found to hydrolyse several synthetic substrates also hydrolysed by chymotrypsin, but with different kinetic constants. 2. Maximal activity against benzoyl-DL-phenylalanine 2-naphthol ester and azo-casein was in the range pH 7.5-8.0. 3. The sensitivity of cathepsin G to the action of potential inhibitors was determined, and compared with those of bovine chymotrypsin and subtilisin. Cathepsin G showed the characteristics of a serine proteinase, but was less affected by the chloromethyl ketone of tosylphenylalanine than was chymotrypsin. 4. A rabbit anti-(human cathepsin G) serum was raised, and precipitin lines formed in agarose gel were stained for activity of the enzyme. 5. Cathepsin G was shown to be immunologically identical with the chymotrypsin-like enzyme of the azurophil granules of the neutrophil granulocytes.
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PMID:Human cathepsin G. Catalytic and immunological properties. 0 45

The reactions between yeast carboxypeptidase C and the group-specific reagents, phenylglyoxal and iodoacetamide, have been studied in detail and the reactions of residue at the active site with N-tosyl-L-phenylalanine chloromethyl ketone and diisopropyl phosphorofluoridate have been confirmed. Modification of the enzyme by either phenylglyoxal or iodoacetamide results in the loss of peptidase activity, while esterase activity remains unchanged. Inactivation by phenylglyoxal appears to be the result of the modification of a single arginine residue, whereas inhibition by iodoacetamide can be correlated with the modification of a single methionine residue. Inactivation of the enzyme by either N-tosyl-L-phenylalanine chloromethyl ketone or diisopropyl phosphorofluoridate is the result of the modification of a single histidine and a single serine residue, respectively. The pattern of inhibition indicates certain analogies in the mechanism of yeast carboxypeptidase C to pancreatic chymotrypsin, on the one hand, and to carboxypeptidase A, on the other.
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PMID:Reaction of yeast carboxypeptidase C1 with group-specific reagents. 1 Sep 62

Heparin forms a complex with chymotrypsin which is active towards glutaryl-L-phenylalanine-p-nitroanilide (GPANA) and glutaryl-L-phenylalanine-beta-naphthylamide (GPNA) at pH 7.6. The activity of chymotrypsin towards GPANA at pH 7.6 is enhanced in the presence of heparin. Heparin does not bind at the active site of the enzyme since proflavin is not displaced from the active site of chymotrypsin upon complex formation. The heparin-chymotrypsin complex migrates under basic polyacrylamide disc gel electrophoresis conditions to a position intermediate between heparin and free chymotrypsin. The complex is dissociable under acidic polyacrylamide gel electrophoresis conditions. It is estimated that one to three molecules of heparin can bind to each chymotrypsin molecule on the basis of electrophoretic and enzymic activity data.
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PMID:Characterization of the interaction between chymotrypsin and heparin. 1 74

A proteolytic enzyme, which causes the limited degradation of cardiac myosin, was purified from rat heart myofibrils. The purified enzyme (a myosin-cleaving protease) was apparently homogeneous by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. Autolysis of the purified enzyme was observed at neutral pH without high concentration of CaCl2. The molecular weight was estimated to be 26 000-27 000. The enzyme was active against casein, N-acetyl-L-tyrosine ethyl ester and N-glutaryl-L-phenylalanine-4-nitroanilide (Glu-Phe-NAn), but less active with N-benzoyl-DL-arginine-4-nitroanilide. Optimum pH values for the enzyme were 9.0 for casein and 8.4 for Glu-Phe-NAn. Caseinolytic activity of the enzyme was completely inhibited with phenylmethylsulfonyl fluoride and diisopropylphosphofluoride and partially inhibited with L-1-tosyl-L-phenylalanine chloromethyl ketone (Tos-PheCH2Cl) and soybean trypsin inhibitor. Tos-LysCH2Cl had no effect. Sulfhydryl reagents, metal-chelating agents and metal ions except for Zn2+ had little or no effect on the activity. Degradation of cardiac myosin with the enzyme produced two fragments having molecular weights of 130 000 and 94 000, accompanied by the disappearance of myosin heavy chain and light chain 2. Myosin degradation with the enzyme was more restrictive than with chymotrypsin.
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PMID:Purification and characterization of a myosin-cleaving protease from rat heart myofibrils. 2 66

The Vicia angustifolia proteinase inhibitor was incubated with p-toluenesulfonyl-L-phenylalanine chloromethyl ketone-trypsin (EC 3.4.21.4) and a main product was isolated. The purified product was different to the first trypsin-modified V. angustifolia inhibitor. The C-terminal residues of the new derivative were arginine, which was also the C-terminal of the cleaved antitryptic site; lysine was a newly exposed C-terminal. These results suggest that the new derivative lacks the C-terminal portion of the native inhibitor, which has asparagine at its C-terminus. The liberated C-terminal peptide had the following amino acid sequence: H-Glu-Glu-Val-Ile-Lys-Asn-OH. The derivative lacking the C-terminal hexapeptide still possesses inhibitory activities against trypsin and alpha-chymotrypsin (EC 3.4.21.1), however, its antichymotryptic activity was inactivated by incubation with chymotrypsin at pH 8.0.
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PMID:Isolation and activities of the trypsin-modified Vicia angustifolia proteinase inhibitor lacking carboxyl-terminal hexapeptide. 3 67

The kinetic specificities of BPN' and Carlsberg subtilisins [EC 3.4.21.14] were examined with various nucleus-substituted derivatives of Nalpha-acetylated aromatic amino acid methyl esters for mapping their hydrophobic binding sites in comparison with that of alpha-chymotrypsin. The Carlsberg enzyme was generally much more reactive than the BPN' enzyme due to the larger kcat value. The fact that the two sutilisins hydrolyzed Ac-Tyr(PABz)-OMe, which is a derivative of tyrosine bearing a planar trans-p-phenylazobenzoyl group at the OH-function, with the smallest Km value showed that these enzymes possess a more extended aromatic binding site than has so far been demonstrated. Ac-Phe(4-NO2)-OMe was remarkable in being hydrolyzed with a particularly large kcat value (5,500 +/- 700 s-1 at pH 7.8 for Carlsberg subtilisin). Ac-Phe(4-NO2)-OMe and Ac-Tyr-OMe were distinguished by Carlsberg subtilisin in terms of kcat but not by BPN' subtilisin, suggesting that the specificity site of the former is more sensitive to a small change in size of substituent than that of the latter. Ac-Trp(NCps)-OMe and Ac-Trp(NCps)-OH were bound to the enzyme's active site but in a competitive manner. A difference in the standard free energies of binding between the two enzymes may indicate that the hydrophobic cleft of Carlsberg subtilisin is somewhat deeper and/or narrower than that of BPN' subtilisin.
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PMID:Kinetic specificities of BPN' and Carlsberg subtilisins. Mapping the aromatic binding site. 10 40


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