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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)

There was studied the solid-state enzyme reaction of specific substrate N-succinyl-L-phenylalanine-p-nitroanilide hydrolysis in contact with alpha-chymotrypsin (Cht). It is shown that product yield is dependent on hydration of the protein. The product is formed only when the relative pressure of water vapours (p/ps) was higher than certain magnitude (p/ps) crit; which depends on the amount of the salt in the sample: the higher the salt concentration the lesser the (p/ps) crit value. It is suggested that the counter-ions may interact with some of primary hydration sites of the Cht molecule. Because of that for the formation of the active Cht conformation is enough to bind lesser number of water molecules than in salt-free samples. But in the presence of salt excess in Cht sample it is necessary to bind of the protein surface at least yields to 80 mol H2O/mol Cht.
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PMID:[Solid-state enzymatic reactions. II. Chymotrypsin hydrolysis of N-succinyl-L-phenylalanine n-nitroanilide]. 58 2

Kinetic of the alpha-chymotrypsin catalyzed reversible hydrolytic reaction of methyl N-acetyl-L-phenylalaninate and N-acetyl-L-phenylalanylglycinamide at pH 5.5 and equilibrium conditions has been studied. The rates of the labeled reaction products incorporated into the substrate a different methanol concentrations shows that the reaction proceeds by a compulsory mechanism with the formation of N-acetyl-L-phenylalanine-alpha-chymotrypsin complex. For the amide substrate the data obtained are also in agreement with the compulsory mechanism of its hydrolysis. Equilibrium kinetics of ester and amide substrates hydrolysis has been compared.
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PMID:[Kinetics of alpha-chymotrypsin catalyzed hydrolysis in equilibrium. II. Comparison of ester and amide substrates]. 61 42

The syntheses are described of p-guanidino-L-phenylalanine and some of its derivatives. alpha-N-(p-Toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester is an excellent substrate of bovine trypsin (EC 3.4.21.4) (Km 57 micron; kcat. 320s-1 at pH 7.4-8.0) and a very poor substrate of human thrombin (EC 3.4.21.5) (Km 190 micron, kcat. 0.2s-1) and bovine chymotrypsin (EC 3.4.21.1). The ester inhibits thrombin clotting activity. It also inhibits the amidase and esterase activities of human thrombin, this inhibition being of the mixed type. The inhibition constant, K1, of the order of 1 micron, increases with increasing inhibitor concentration. This suggests that the enzyme binds the inhibitor at multiple sites. The importance of the residue at the P1 position [notation of Berger & Schechter (1970) Philos. Trans. R. Soc. London Ser. B 257, 249-264] in determining the selectivity of a substrate or quasi-substrate among trypsin-like enzymes is borne out. p-Guanidino-L-phenylalanine may have a use in the synthesis of selective peptide inhibitors of thrombin.
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PMID:The interaction of alpha-N-(p-toluenesulphonyl)-p-guanidino-L-phenylalanine methyl ester with thrombin and trypsin. 62 42

1. The chymotrypsin-catalyzed hydrolysis of polyacrylamide-bound L-phenylalanine 4-nitroanilide was studied. As a spacer, one or two 6-aminohexanoyl residues were inserted between the matrix and ligand. 2. In the course of the enzymatic hydrolysis of polyacrylamide-bound substrates, enzyme adsorption by the gel substrates was observed. A quasi equilibrium of enzyme partitioning was reached after approximately 20-min incubation time. The enzyme adsorption could be described by the Langmuir adsorption isotherm. 3. The substrates attached via spacers to the matrix were completely hydrolyzed. 4. The initial course of the product vs time curves, as well as the dependence of the initial hydrolysis rates on enzyme concentration or substrate concentration, have been interpreted by the Nernst reaction theory. From the results obtained it has been concluded that the inital rate of the hydrolysis of polyacrylamide-bound L-phenylalanine 4-nitroanilide depends on the velocity of enzyme diffusion into the matrix.
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PMID:Enzymatic attack on immobilized substrates. 2. Diffusional limitations in the alpha-chymotrypsin-catalyzed hydrolysis of polyacrylamide-bound l-phenylalanine 4-nitroanilide. 68 30

The selective cleavage of peptide bonds by a serine protease from skeletal muscle (SK-protease) was examined using glucagon and neurotensin as substrates. Among the peptide bonds cleaved in these substrates, the most susceptible were Phe-Thr-Ser, Tyr-Leu, Trp-Leu, and Tyr-Ile. These results indicate that the SK-protease hydrolyzed the carboxyl side of aromatic amino acid residues under the experimental conditions. When the amino acid on the carboxyl side of aromatic amino acid residues was serine, threonine or glutamic acid, these peptide bonds, such as Phe-Thr, Tyr-Ser, and Tyr-Glu, were not susceptible to another serine protease from small intestine (SI-protease) under the same experimental conditions. The peptide bond between the arginines of Pro-Arg-Arg-Pro in neurotensin was hydrolyzed by the SI-protease, but not by the SK-protease. Thus the specificity of the SK-protease differs from that of the SI-protease. These results suggest that the specificity of the hydrolytic action of the SK-protease is more like that of bovine chymotrypsin A than like that of porcine chymotrypsin C and of the SI-protease.
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PMID:Selective cleavage of peptide bonds by a serine protease from rat skeletal muscle. 70 Dec 36

Evidence is presented that N-benzyloxycarbonyl-L-phenylalanine vinyl ester and 1,2-dibromoethyl ester are inhibitors of Walker 256 carcinosarcoma and Ehrlich ascites carcinoma tumor growth. The major effects of these two agents on Ehrlich ascites cell metabolism were the inhibition of deoxyribonucleic acid and protein synthesis and the alteration of cellular regulatory processes controlling cytokinetics. Deoxynucleotide (purine) kinase enzymes appeared to be the focal site for inhibition of deoxyribonucleic acid synthesis with marginal inhibition of thymidylate synthetase activity. Cyclic adenosine monophosphate levels were elevated by drug treatment whereas chromatin protein phosphorylation, cell respiration, and lysosomal activities were inhibited. N-Benzyloxycarbonyl-L-phenylalanine 1,2-dibromoethyl ester was a latent in vitro chymotrypsin inhibitor. Some preliminary evidence suggests that these activated esters may inhibit cellular enzymatic activity by alkylating imidazole and lysine residues of proteins.
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PMID:Antineoplastic agents III: effects of dibromoethyl and vinyl esters of N-benzyloxycarbonyl-l-phenylalanine on Ehrlich ascites tumor cell metabolism. 72 89

The acetylpeptides derived from S-carboxymethylovalbumin by cyanogen bromide and chymotrypsin have been isolated and shown by enzyme digestion and the dansyl-Edman method to fit the sequence acetyl-Gly-Ser-Ile-Gly-Ala-Ala-Ser-Met-Glu-Phe. This corrects the order of the third and fourth residues in the five-residue sequence given by Narita and Ishii [J. Biochem. (Tokyo), 1962, 52, 367--73]. The overlap of the C-terminal sequence of this extended sequence with the six-residue N-terminal sequence surrounding a half-cystine residue in ovalbumin gives the N-terminal sequence for ovalbumin as acetyl-Gly-Ser-Ile-Gly-Ala-Ala-Ser-Met-Glu-Phe-Cys-Phe-Asp-Val-Phe-Lys with residue 11 a cysteine residue.
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PMID:A correction and extension of the acetylated amino terminal sequence of ovalbumin. 75 25

Protease I, a periplasmic endopeptidase from Escherichia coli has been further purified by a modified procedure. While the purified protein consists of a single polypeptide chain of about 21000 daltons, its molecular weight in dilute salt solution was estimated to be near 43000, suggesting that the enzyme has a marked tendency to dimerize. It has only one disulphide bond and is very sensitive to urea. In agreement with previous evidence of a chymotrypsin-like specificity, hydrolytic assays of various p-nitrophenyl esters of N-substituted amino acids showed that phenylalanine and tyrosine derivatives are the best substrates for the enzyme. The Km(app) for N-benzoyloxycarbonyl-L-tyrosin-p-nitrophenyl ester at pH 7.5 In 100 mM sodium phosphate buffer at 25 degrees C was found to be 0.2 mM. In contrast to chymotrypsin, protease I is unable to hydrolyse N-acetyl-L-phenylalanine ethyl ester and its tyrosine analogue. Moreover, the enzyme appears devoid of amidase activity and exhibits a low activity upon polypeptides. At 37 degrees C, it cleaves the carboxymethylated B-chain of bovine insulin at four points: Phe25-Tyr26, Phe24-Phe25, Leu15-Tyr16 and Ser9-His10. From a detailed study of peptides bonds hydrolyzed, it was concluded that protease I has a stringent requirement for both residues forming the scissile bond, and appears to possess an extended hydrophobic binding site.
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PMID:Protease I from Escherichia coli. Some physicochemical properties and substrate specificity. 79 43

Human granulocyte elastase (EC 3.4.21.-) was isolated and purified (yield = 62%, purity = 91-100%) by a new short procedure using affinity chromatography using phenylbutylamine covalently linked to Affi-Gel. The granulocyte elastase was found to have a molecular weight of 34 400 by sodium dodecyl sulphate gel electrophoresis and the molecular weight obtained from the amino acid composition was 34 970. The composition of elastase purified from normal leucocytes showed some significant differences from that of enzyme purified by others from leukemic leucocytes. The granulocyte elastase hydrolysed typical pancreatic elastase substrates like Boc-Ala-ONp and Ac-(Ala)3-Nan. The enzyme was also found to have a weak enzymatic activity in hydrolysing acetyl-L-phenylalanine-alpha-naphthyl ester, a typical chymotrypsin substrate. A monospecific antiserum raised against the purified enzyme gave a single precipitin line with the pure enzyme and also with crude granular extract, both lines being identical.
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PMID:A rapid method of purification of human granulocyte cationic neutral proteases: purification and further characterization of human granulocyte elastase. 81 Jan 68

The stereospecific hydrolysis of D,L-phenylalanine methylester with immobilized alpha-chymotrypsin was carried out as a model reaction for the racemate resolution of aromatic amino acids in a five staged fluidized-bed reactor (FBR). Owing to ester hydrolysis, a pH shift occurred along the reactor. Because of the pH-dependent enzyme activity a particular longitudinal pH profile had to be enforced by a proper entrance pH in order to gain an optimum conversion. In the FBR with optimum pH profile, higher conversions were achieved than in a continuous stirred tank reactor (CSTR) at the pH optimum and at the same contact time. By the application of a proton balance and the results of kinetic measurements a model was developed for the prediction of the optimum longitudinal pH profile with regard to the maximum conversion.
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PMID:Application of immobilized chymotrypsin in a multistage fluidized-bed reactor. 92 29


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