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)

Thin-layer isoelectric focusing of chymotrypsin modified by stepwise acylation with acryloyl chloride or maleic anhydride revealed a high heterogeneity of modification products, with a maximal number of components near 50% of substituted amino groups. Disc electrophoresis failed to establish the products diversity and could not therefore be used for heterogeneity control. The activity of the modified enzyme towards proteins and low molecular weight substrates depended on the modification reagent and correlated with the electrostatic enzyme--substrate interaction. The low hydrolytic activity towards N-acetyl-L-tyrosine p-nitroanilide was due to the increase in the Michaelis constant; the value of the catalytic constant remained unchanged.
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PMID:[The heterogeneous character of protein modification during substitution of their amino groups. Acylation of alpha-chymotrypsin]. 663 86

In various studies during recent years, the use of p-aminobenzoic acid has been described in screening tests for exocrine pancreatic function. A synthetic three-unit compound N-benzoyl-L-tyrosyl-p-aminobenzoic acid has been administered orally and hydrolysed in the small intestine in the presence of chymotrypsin to N-benzoyl-L-tyrosine and p-aminobenzoic acid. This study describes a convenient procedure in which, after a selective extraction and derivatization with diazomethane, capillary gas chromatography is used combined with nitrogen-sensitive detection. With the proposed procedure, p-aminobenzoic acid and its major metabolites, acetyl-p-aminobenzoic acid and p-aminohippuric acid, can be monitored in serum and in urine samples.
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PMID:Simultaneous determination of p-aminobenzoic acid, acetyl-p-aminobenzoic acid and p-aminohippuric acid in serum and urine by capillary gas chromatography with use of a nitrogen-phosphorus detector. 697 21

Study of the temperature dependence of hydrolysis of the ethyl ester N-acetyl-L-tyrosine and p-nitroanilide N-succinyl-L-phenylalanine by chymotrypsin and polymaleic acid-modified chymotrypsin showed that the enthalpy and enthropy of dissociation of the enzyme-substrate complex and those of activation of the enzyme acylation in the course of catalysis increase during the native enzyme transition to its modified form. The data obtained can be explained terms of changes in the native conformation of the enzyme during its modification, which is confirmed by the previously obtained data on thermodenaturation. Some part of the energy of substrate binding is consumed for changing the conformation of the modified protein, rendering it close to the native one and thus providing a further enzymatic catalysis which is similar to that by the native enzyme.
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PMID:[Thermodynamics changes in catalytic properties of immobilized enzymes]. 706 22

A photometric method for chymotrypsin is proposed, using the substrate N-acetyl-L-tyrosine ethyl ester, which is already used in the titrimetric procedure. Hydrolysis of the ester bond produces equal amounts of ethanol and acetyltyrosine, the latter being measured in the titrimetric method. The ethanol can easily be measured by the alcohol dehydrogenase method in the trichloroacetic acid supernatant. Suitable test conditions are reported.
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PMID:Faecal chymotrypsin--a new photometric method using N-acetyl-L-tyrosine ethyl ester as substrate. 707 29

A variety of platinum complexes were evaluated as inhibitors of alpha-chymotrypsin. A standard enzyme assay was used with benzoyl-L-tyrosine ethyl ester as the substrate. Rb2PtBr4, trans-Pt(NH3)2Cl2, and K2PtCl4 were all effective enzyme inhibitors. Pt(Gly-L-Met(Cl2, Pt(Met)(NH3)2Cl, cis-Pt(NH3)2Cl2, and two ethylenediamminedichloroplatinum complexes were weak inhibitors of alpha-chymotrypsin. A surprising finding was the noninhibition of an immobilized preparation of alpha-chymotrypsin by the above inhibitors and by active-site-directed modifying reagents.
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PMID:Effects of platinum complexes on chymotrypsin. 719 Jan 92

The synthesis of 5-carboxyvaleryl- and 3-carboxypropionyl-L-phenylalanine beta-naphthyl ester (Adi-Phe-ONap, Suc-Phe-ONap) and 3-carboxypropionyl-L-phenylalanine p-nitrophenyl ester (Suc-Phe-ONp) is reported. The two latter compounds were obtained in good yields by 3-carboxypropionylation of the L-phenylalanine aryl esters with succinic anhydride at pH values below 6 in aqueous organic solutions. The beta-naphthyl esters in particular proved to be sensitive substrates for cathepsin G and chymotrypsin. They are not or only slightly hydrolyzed by other proteinases like elastases, kininogenases, e.g. kallikrein, plasmin, thrombin and trypsin. The spontaneous hydrolysis of the beta-naphthyl esters is relatively slow below pH 8. beta-Naphthol split-off during the enzyme reaction may be conveniently monitored at 328.5 nm (epsilon = 1730M-1 X cm-1) or with an at least 15-fold increase in sensitivity in a discontinuous assay after coupling with Fast Garnet at 520 nm (epsilon = 34800M-1 X cm-1). The increase in absorbance is linear with time and proportional to the amount of enzyme up to A 328.5 of at least 0.62. Adi-Phe-ONap is preferentially used for cathepsin G (at 328.5 nm 9.2-fold more sensitive than benzoyl-L-tyrosine ethyl ester, Bz-Tyr-OEt) whereas for chymotrypsin Suc-Phe-ONap is more advantageous (4.2-fold increase in sensitivity at 328.5 nm over Bz-Tyr-OEt). The influence of dimethyl sulphoxide and Brij 35 on the activity of cathepsin G and chymotrypsin was investigated using Suc-Phe-ONap as the substrate. The values of Km and kcat were determined for both enzymes and substrates. Because of the relatively high rates of spontaneous hydrolysis above pH 7.0 the use of Suc-Phe-ONp is less advantageous.
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PMID:[Synthesis of omega-carboxyacyl-L-phenylalanine-aryl esters and their use as substrates for cathepsin G and chymotrypsin]. 727 4

The inhibition of alpha-chymotrypsin by horse leucocyte neutral proteinases inhibitor was time-dependent with synthetic substrate N-benzoyl-L-tyrosine ethyl ester but not with azo-casein. This time dependence could be used to calculate the rate constant kass for the association of the inhibitor with bovine alpha-chymotrypsin (kass = 0.3 X 10(6)M-1 S-1). The inhibitor reacted with chymotrypsin at a molar a ratio of 1 : 1. The dissociation constant Ki = 0.30 X 10(9)M of the complex indicates a very strong interaction between enzyme and inhibitor.
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PMID:The interaction between chymotrypsin and horse leucocyte neutral proteinases inhibitor. 730 99

Polyacrylamide beads (microgranules) containing covalently bound alpha-chymotrypsin were obtained. An average diameter of the microgranules is 100--150 micrometers. Prior to the bead polymerization alpha-chymotrypsin was modified by acryloyl chloride. The efficiency of the microgranulated alpha-chymotrypsin action depends on the kinetic properties of the substrates used. The pH optimum for the microgranulated enzyme activity towards N-acetyl-L-tyrosine ethyl ester is shifted by 1,5 units to the alkaline zone. The immobilized alpha-chymotrypsin is completely stable for 100 hrs at 50 degrees.
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PMID:[Properties of alpha-chymotrypsin, covalently incorporated into polyacrylamide microgranules]. 737 83

The metacestodes of Taenia pisiformis have been shown to contain a protease inhibitor capable of inactivating the esterolysis of N-alpha-benzoyl-L-arginine ethyl ester (BAEE) and N-benzoyl-L-tyrosine ethyl ester (BTEE) by trypsin and chymotrypsin, respectively, of bovine, dog and rabbit origin, but not affecting the hydrolytic activity of subtilisin, elastase, collagenase, pepsin, rennin and papain. This inhibitor has been demonstrated in whole worm extracts and in the incubation medium of in vitro-maintained, intact living metacestodes. The protease inhibitor which was purified by trichloroacetic acid precipitation, Sephadex G-100 chromatography and affinity chromatography on CNBr-activated Sepharose 4B-bovine, chymotrypsin conjugate was soluble in 5% trichloroacetic acid, withstood heat up to 80 degrees C, tolerated the pH range 1.5 to 9.0, was unaffected by 8 M urea or 0.2 M 2-mercaptoethanol and had a molecular weight of about 7000 to 7200, as calculated from its gel chromatographic behaviour. Complex formation between the inhibitor and the enzymes required 3--4 min for completion. The enzyme-inhibitor complex was not dissociated by 4 M KCl. Activity determinations on bovine TPCK-trypsin and bovine chymotrypsin with BAEE and BTEE assays revealed that the inhibitory actions toward both enzymes are functions of the same or closely adjacent sites of the inhibitor molecule. The supposed function of the inhibitor is discussed.
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PMID:A trypsin and chymotrypsin inhibitor from the metacestodes of Taenia pisiformis. 739 18

CPY is a metal-free carboxypeptidase from yeast with broad specificity [1]. In addition to exopeptidase activity at acid pH, the enzyme is an effective esterase at alkaline pH. N-alpha-acetyl-L-tyrosine ethyl ester is hydrolyzed faster by CPY than by chymotrypsin. These observations suggested that the immobilized form of the enzyme would be of value in removing ester groups from the C-terminal ends of peptides. In this report we describe sequential synthesis using I-CPY and alpha-COOH deblocking of peptides made by conventional methods.
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PMID:Use of immobilized carboxypeptidase Y (I-CPY) as a catalyst for deblocking in peptide synthesis. 741 89


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