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)

Nucleophilic properties of amino-acid amides were studied systematically in acyl-transfer reactions catalyzed by alpha-chymotrypsin and subtilisin from Bacillus subtilis strain 72 (subtilisin 72) using Mal-L-Ala-L-Ala-L-PheOMe as the acyl-group donor. In alpha-chymotrypsin-catalyzed reactions, the nucleophile reactivities increase in the following order: D-AlaNH2 < GlyNH2 < L-AlaNH2 < L-SerNH2 < L-ThrNH2 < L-HisNH2 < L-ValNH2 < L-LeuNH2 < L-TrpNH2 < L-MetNH2 < L-NvaNH2 < L-PheNH2 < L-IleNH2 < L-TyrNH2 < L-ArgNH2. In reactions catalyzed by subtilisin 72, the reactivities increase as follows: L-LeuNH2 < L-IleNH2 < L-ThrNH2 < L-ArgNH2 < L-TrpNH2 < L-NvaNH2 < L-ValNH2 < L-MetNH2 < L-AlaNH2 < L-SerNH2 < D-AlaNH2 < GlyNH2. In alpha-chymotrypsin-catalyzed reactions, hydrophobic interactions are entirely responsible for the differences between the reactivity of the nucleophiles for amides of all the amino-acids tested with the exception of D-AlaNH2, L-ArgNH2 and L-TyrNH2. In reactions catalyzed by subtilisin 72, amino-acid side-chain characteristics and the nucleophile reactivities are not related. The data obtained show the low selectivity of the S1' subsite of subtilisin 72 and high specificity of this subsite in alpha-chymotrypsin.
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PMID:Nucleophile specificity in alpha-chymotrypsin- and subtilisin-(Bacillus subtilis strain 72) catalyzed reactions. 144 45

Alpha-chymotrypsin-catalyzed acyl transfer from Boc-L-MetONp, Ac-L-TyrOEt, Bz-L-TyrOMe, Mal-L-PheOMe to the C-protected amino acids (L-AlaNH2, L-LeuNH2, L-ArgOMe and beta-naphthylamides of L-Arg, L-Leu, L-Ala and L-Glu) has been studied. Modification of the carboxylic groups with beta-naphthylamide was shown to increase the reactivity of nucleophiles in these reactions by a factor of more than 100 in comparison with amides and esters of the same amino acids. This effect can be accounted for by the effective formation of the nucleophile-acylenzyme complex due to hydrophobic interactions of the beta-naphthylamide moiety with the corresponding subsite of alpha-chymotrypsin. The reaction kinetics follows the scheme involving hydrolysis of the nucleophile-acylenzyme intermediate. The contribution of this pathway depends on the structures of both the acyl-group donor and the added nucleophile. The competitive inhibition by amino acid beta-naphthylamides is also observed. The results obtained show that modification of the COOH-group of added nucleophiles by beta-naphthylamide strongly affects the reactivity of these compounds in the alpha-chymotrypsin-catalyzed peptide synthesis.
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PMID:Increased nucleophile reactivity of amino acid beta-naphthylamides in alpha-chymotrypsin-catalyzed peptide synthesis. 222 49

The alpha-chymotrypsin (EC 3.4.21.1)-catalyzed reaction of Mal-Phe-OMe with H-Leu-NH2 has been studied under a range of reaction conditions, for example various cryogenic reagents for shock-freezing, addition of dimethyl sulfoxide (DMSO) and decreased reaction temperatures down to 213 K. It has been shown that the peptide yield is independent of the method of shock-freezing. The optimal reaction temperature was between 263 K and 248 K. Lower temperatures result in clearly retarded reactions. Addition of DMSO leads to decreasing peptide yields. It is certain that the peptide bond formation is catalyzed by the active enzyme, since unspecific protein surface catalysis gave no peptide yields at all.
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PMID:Enzymatic peptide synthesis in frozen aqueous systems: influence of modified reaction conditions on the peptide yield. 771 Jun 98

The progress of enzymatic peptide synthesis catalyzed by alpha-chymotrypsin and subtilisin from Bacillus subtilis strain 72 (subtilisin 72) in low-water systems was studied. The initial reaction mixture consisted of the solvent, the acyl-group donor (MalAlaAlaPheOMe or ZAlaAlaPheOMe, Mal, maleyl, Z, benzyloxycarbonyl), the nucleophile XaaNH2 (Xaa = Phe, Leu or Ala), and the enzyme adsorbed on porous silica material. All amino acid residues were of the L-configuration. The solvent consisted of acetonitrile, dimethylformamide (DMF), and 4% (v/v) of water. The DMF/acetonitrile ratio was varied between 0 and 1/1. At high concentration of the acyl-group donor and approximately equimolar ratio of the nucleophile and the acyl-group donor, quantitative formation of MalAlaAlaPheXaaNH2 or ZAlaAlaPheXaaNH2 occurred. As a result, a method for the synthesis of polypeptide amides was developed. At low concentration of the acyl-group donor and excess of the nucleophile, the condensation by-products with two and three nucleophile molecules were found in the reaction mixtures. The data obtained provided evidence that organic solvents affected the S'1-specificity of alpha-chymotrypsin and the S1-specificity of subtilisin 72, while the S1-specificity of alpha-chymotrypsin and the S'1-specificity of subtilisin 72 were not affected. When the DMF content was increased, the rate of the alpha-chymotrypsin-catalyzed reactions decreased. In contrast to this, an increase in DMF content accelerated the subtilisin 72-catalyzed reactions. Hydrolysis of the acyl-group donor did not occur in the alpha-chymotrypsin-catalyzed reactions. Significant (up to 50%) formation of MalAlaAlaPheOH was observed at the early stage of the subtilisin 72-catalyzed reactions. Later MalAlaAlaPheOH underwent synthesis.
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PMID:Side reactions in enzymatic peptide synthesis in organic media: effects of enzyme, solvent, and substrate concentrations. 776 92

alpha-Chymotrypsin-catalyzed acyl transfer was studied using three acyl-group donors (Mal-L-Ala-L-Ala-L-PheOMe, Bz-L-TyrOEt and Ac-L-TrpOEt; Mal, maleyl; Bz, benzoyl; OMe, methyl ester; OEt, ethyl ester) and a series of amino-acid amides. Most of the reactions studied can be described by the simplest kinetic model without the nucleophile binding to the acyl-enzyme. The alpha-chymotrypsin-catalyzed transfer of the Mal-L-Ala-L-Ala-L-Phe group to the amides of L-Phe and L-Tyr showed a linear dependence of the partition constant, p, on the nucleophile concentration which can be interpreted by the hydrolysis of the acyl-enzyme-nucleophile complex. The alpha-chymotrypsin-catalyzed transfer of the Bz-L-Tyr and Ac-L-Trp groups to several amino-acid amides showed unusual behavior which can be interpreted by the kinetic model involving formation of a complex of the acyl-enzyme with two nucleophile molecules. These observations can explain the conflicting conclusions concerning the kinetics of alpha-chymotrypsin-catalyzed acyl transfer evident in previous studies.
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PMID:The second nucleophile molecule binds to the acyl-enzyme-nucleophile complex in alpha-chymotrypsin catalysis. Kinetic evidence for the interaction. 822 53

The influence of eight different N-terminal protecting groups (For, Ac, Boc, Fmoc, Mal, Pheac, Aloc and Z) on the alpha-chymotrypsin-catalyzed synthesis of the dipeptide derivative X-Phe-Leu-NH2 in organic media was studied. Groups such as Ac, For, Boc, Z, Mal, Pheac and Alloc always rendered good peptide yields (92% to 99%) either in acetonitrile or in ethyl acetate. Good correlations were found between molecular and physico-chemical characteristics of the N-alpha moiety such as the hydrophobicity (log P), ovality and dipole moment and the global reaction rate parameter k'. High k' values were obtained with the less hydrophobic groups, Ac, For and Mal, that have ovality values close to one and the highest dipole moments. Furthermore, it was found that the relative rate of hydrolysis and aminolysis of the acyl-enzyme intermediate expressed as the partition parameter p is affected by the N-alpha moiety of the acyl donor. Correlations between this parameter and the dipole moment of the protecting group were observed.
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PMID:Enzymatic synthesis of X-Phe-Leu-NH2 in low water content systems: influence of the N-alpha protecting group and the reaction medium composition. 832 50