Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

From a crude extract of chick peas (Cicer arietinum L.) inhibitors of trypsin and chymotrypsin were isolated by affinity chromatography on a column of trypsin-Sepharose 6B. The content of inhibitors was found to be 1.5 g/kg. They were further separated into six isoinhibitors by ion-exchange chromatography on DEAE-Sephadex A-25. Two of the isoinhibitors accounted for about 50% of the isolated inhibitors and were further purified to a homogeneous state. The isoinhibitors had a molecular weight of about 10000 as determined by molecular-sieve chromatography on Sephadex G-75. They were stable towards extremes of pH and temperatures up to 75 degrees C or towards digestion by pepsin. They were also stable in 6 M urea but not in 6 M guanidine-HCl. The intact inhibitors were destroyed when the peas were cooked at 100 degrees C or when they were toasted at 130 degrees C. The four major inhibitors had similar amino acid compositions and did not contain detectable amounts of free sulfhydryl groups, tryptophan or carbohydrate. Cysteine is the dominant amino acid residue in all of them and accounted for about 20% of their amino acid content. The isoelectric point of the isoinhibitors lies in the range of pH 4.9-8.6 and two of the major inhibitors had isoelectric points of pH 4.75 and pH 4.96. They inhibited chymotrypsin to the same extent but differed in their inhibitory activities towards trypsin, indicating that they are mixtures of native and trypsinmodified forms and that they probably have separate sites for the two enzymes. They did not inhibit other proteolytic enzymes belonging to two groups (i.e., serine or cysteine enzymes) or originating from different sources (i.e., animals, plants or bacteria).
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PMID:The trypsin and chymotrypsin inhibitors in chick peas (Cicer arietinum L.). Purification and properties of the inhibitors. 0 Dec 66

Two proteinase inhibitors, designated as inhibitors I and II, were purified from adzuki beans (Phaseolus angularis) by chromatographies on DEAE- and CM-cellulose, and gel filtration on a Sephadex G-100 column. Each inhibitor shows unique inhibitory activities. Inhibitor I was a powerful inhibitor of trypsin [EC 3.4.21.4], but essentially not of chymotrypsin ]EC 3.4.21.1]. On the other hand, inhibitor II inhibited chymotrypsin more strongly than trypsin. The molecular weights estimated from the enzyme inhibition were 3,750 and 9,700 for inhibitors I and II, respectively, assuming that the inhibitions were stoichiometric and in 1 : 1 molar ratio. The amino acid compositions of both inhibitors closely resemble those of low molecular weight inhibitors of other leguminous seeds: they contain large amounts of half-cystine, aspartic acid and serine, and little or no hydrophobic and aromatic amino acids. Inhibitor I lacks both tyrosine and tryptophan residues. The molecular weights were calculated to be 7,894 and 8,620 for inhibitors I and II, respectively. The reliability of these molecular weights was confirmed by the sedimentation equilibrium and 6 M guanidine gel filtration methods. On comparison with the values obtained from enzyme inhibition, it was concluded that inhibitor I and two trypsin inhibitory sites on the molecule, whereas inhibitor II had one chymotrypsin and one trypsin inhibitory sites on the molecule.
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PMID:Purification and characterization of proteinase inhibitors from adzuki beans (Phaseolus angularis). 0 91

Two new double-headed protease inhibitors from black-eyed peas have amino acid compositions typical of the low molecular weight protease inhibitors from legume seeds. Black-eyed pea chymotrypsin and trypsin inhibitor (BEPCI) contains no tryptophan, 1 tyrosine, and 14 half-cystines out of 83 amino acid residues per monomer. Black-eyed pea trypsin inhibitor (BEPTI) contains no tryptophan, 1 tyrosine, and 14 half-cystines out of 75 residues per monomer. The molar extinctions at 280 nm are 2770 for BEPCI and 3440 for BEPTI. The single tyrosyl residue is very inaccessible to solvent in native BEPCI and BEPTI at neutral pH and titrates anomalously with an apparent pK = 12. Ionization of tyrosine is complete in 13 hours above pH 12. No heterogeneity of the local environment of the tyrosyl residues in different subunits can be detected spectrophotometrically. The large number of cystine residues leads to an intense and complex near-ultraviolet CD spectrum with cystine contributions in the regions of 248 and 280 nm and tyrosine contributions at 233 and 280 nm. An intact disulfide structure is required for appearance of the tyrosyl CD bands. The inhibitors are unusually resistant to denaturation when compared with similar low molecular weight proteins of high disulfide content. All observations are consistent with a far more rigid structure for BEPCI and BEPTI than for a typical protein.
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PMID:Double-headed protease inhibitors from black-eyed peas. II. Structural studies by optical absorption and circular dichroism. 0 93

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

The radiation yeilds of unfolding (Gconf) determined by the method of tryptophan fluorescence coincide with the radiation yields of proteolytic inactivation (Gin) for chymotrypsin-like (CT-like) enzymes on irradiation in air, both in solution and in the dry state with futher dissolution at pH7. It can be supposed that the unfolding is the main process determining the proteolytic gamma-inactivation of CT-like enzymes. It was also shown that the transition of chymotrypsin and trypsin gamma-irradiated at acid pH to neutral pH is an additional action, leading to unfolding of part of the molecules.
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PMID:Gamma-irradiated chymotrypsin-like proteins. II. Connection between inactivation and structural changes. 1 28

The interaction between alpha-chymotrypsin [EC 3.4.21.1] and peptide substrate or peptide inhibitor was investigated to determine how the secondary interaction influences the rate of hydrolysis or the binding and whether or not its effect is variable with alteration of the P1 residue which interacts with the specificity determining site of the enzyme. Kinetic analysis was carried out at pH 6.5 and 7.8 for substrates of the type Ac-Glyn-X-OMe and for inhibitors of the type Ac-Glyn-X-OH where X denotes tryptophan or its derivatives. With substrates containing tryptophan or Nin-formyltryptophan, the second-order rate of hydrolysis increases with increase of chain length. With substrates containing 2-(2-nitro-4-carboxyphenylsulfenyl)-tryptophan, however, the rate of hydrolysis decreases with elongation of the chain, due to an increase in Km(app). The corresponding inhibitors behave differently from the other series of inhibitors at pH 6.5. The results indicate that the influence of the secondary interaction on reactivity or binding is related to the structural features of the P1 residue.
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PMID:Interactions of alpha-chymotrypsin with peptides containing tryptophan or its derivatives at the C-terminus. 1 55

The alterations of tryptophan fluorescence parametres with pH may be due to: 1) conformational changes; 2) changes in the ionic state of groups capable of quenching the tryptophan fluorescence. The applications of the model of discrete forms of tryptophan allow one to separate these mechanisms and estimate the middle points of conformational changes and pK's of quenching groups. For chymotrypsin (CT) and chymotrypsinogen (CTG) conformational changes were registrated with middle points: CT pH 4.1 and 8.8; CTG -- pH 3.2 and 9.8, and pK's of histidines: CT -- 5.4 and 6.6; CTG -- 5.6 and 7.0. For trypsin conformational changes were shown with middle points: pH 3.2; 5.8; 8.5 and for lysozyme -- pH 5.9.
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PMID:[pH-dependence of fluorescence parameters of chymotrypsin, chymotrypsinogen, trypsin and lysozyme]. 3 49

The reaction of alpha-chymotrypsin with N alpha-3-(2-furyl)acryloyl-L-tryptophan methyl ester (FA-Trp-OMe) and amide has been investigated in aqueous and dimethylsulphoxide cryosolvent solutions from pH2 to 7 and over a wide temperature range. Previous reports have suggested that an intermediate preceding the acyl-enzyme can be detected spectrophotometrically in the reaction with methyl esters of FA-Trp and FA-Tyr at low pH [Yu & Viswanatha (1969) Eur. J. Biochem. 11, 347--352), and that this intermediate is an oxazolinone [Coletti-Previero et al. (1970) FEBS Lett. 11, 213--217]. We show that the previous interpretations of the time-dependent spectral changes were incorrect, and that the only detected intermediate is the acyl-enzyme. This may be isolated by gel filtration at pH less than 2.5, 1 degree C, owing to its relative stability. The pH-dependence of the rates of acylation and deacylation from pH 8.5 to 2.0 are consistent with a single ionization of pK congruent to 7.0 in both aqueous and cryosolvent solutions.
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PMID:Reinvestigation of the reaction of chymotrypsin with N-furylacryloyltryptophan derivatives at acidic pH. 4 87

Five protease inhibitors, I--V, in the molecular weight range 7000--8000 were purified from Tracy soybeans by ammonium sulfate precipitation, gel filtration on Sephadex G-100 and G-75, and column chromatography on DEAE-cellulose. In common with previously described trypsin inhibitors from legumes, I--V have a high content of half-cystine and lack tryptophan. By contrast with other legume inhibitors, inhibitor II contains 3 methionine residues. Isoelectric points range from 6.2 to 4.2 in order from inhibitor I to V. Molar ratios (inhibitor/enzyme) for 50% trypsin inhibition are I = 4.76, II = 1.32, III = 3.22, IV = 2.17, V = 0.97. Only V inhibit chymotrypsin significantly (molar ratio = 1.33 for 50% inhibition). The sequence of the first 16 N-terminal amino acid residued of inhibitor V is identical to that of the Bowman-Birk inhibitor; all other observations also indicate that inhibitor V and Bowman-Birk are identical. The first 20 N-terminal amino acid residues of inhibitor II show high homology to those of Bowman-Birk inhibitor, differing by 1 deletion and 5 substitutions. Immunological tests show that inhibitors I through IV are fully cross-reactive with each other but are distinct from inhibitor V.
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PMID:Purification, partial characterization, and immunological relationships of multiple low molecular weight protease inhibitors of soybean. 7 87

1. A serine protease of hepatoma 8999, isolated in the mitochondrial fraction, was purified and crystallized. The purified enzyme was apparently homogeneous on ultracentrifugal analysis and polyacrylamide disc gel electrophoresis. The ratio of absorbance at 280 nm and 260 nm, A280/A260, was 1.90 and its absorption coefficient, A280 1% was 10.5 cm-1 estimated from dry weight measurements. Its S20, w value was 2.23 S and its molecular weight was estimated to be 24000 +/- 1000. The enzyme contained twice as much lysine, arginine and histidine as chymotrypsinogen did, but had a very similar amino acid composition to serine protease from skeletal muscle. Its isoelectric point was pH 10.6. 2. The substrate specificity of the enzyme was the same as that of chymotrypsin A. Its Km and kcat values for N-acetyl-L-tyrosine ethyl ester, N-acetyl-L-phenylalanine ethyl ester and N-acetyl-L-tryptophan ethyl ester were 0.35 mM and 10.69 s-1, 0.38 mM and 10.7 s-1, and 0.11 mM and 11.8 s-1, respectively. Its activity was completely inhibited by phenylmethylsulfonyl fluoride and partially inhibited with tosylphenylalanine chloromethyl ketone. 3. The enzyme was shown to be located in different granules from the intracellular particules (light and heavy mitochondrial fraction) by sucrose density gradient centrifugation, and it was stained in mast cells of the hepatoma 8999 by the immunofluorescent technique. 4. Serine protease is present in different amounts in various organs of rat and the enzyme from hepatoma 8999 gave a single band that fused completely with those of the enzymes from skeletal muscle, heart, liver and kidney, respectively, on Ouchterlony double-diffusion analysis using antiserum to the crystalline enzyme of hepatoma 8999, but the enzyme from small intestine did not react with the antiserum.
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PMID:Purification, characterization and localization of serine protease of Morris hepatoma 8999. 11 11


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