The catalytic activity of pig pepsin C towards small synthetic substrates.

C A Auffret; A P Ryle

doi:10.1042/bj1790239

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The catalytic activity of pig pepsin C towards small synthetic substrates.

C A Auffret·A P Ryle

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Abstract

A series of small peptides has been synthesized and used to investigate the activity of a minor pig pepsin, pepsin C (EC 3.4.23.3). The peptides had the general formula A-Leu-Val-His-B. B was either OMe, NH2 or OH. With B = NH2 hydrolysis (kcat./Km) at 37 degrees C and pH 2.07 increased as A was Ac-Ala, Ac-Tyr, Ac-Phe and Ac-Ala-Phe. The pH dependence of the hydrolysis of Ac-Phe-Leu-Val-His-NH2 indicated the apparent pKa values of two catalytically important groups on the enzyme as 1.42 and 4.88. Inhibition of the hydrolysis of the same peptide by Ac-Phe at pH 3.01 showed a form of mixed non-competitive inhibition. Hydrolysis of Ac-Tyr-Leu-Val-His-OMe and the corresponding amide showed non-classical kinetics, which are discussed in terms of a substrate-activating mechanism. The results are discussed with reference to observations made by other workers on pig pepsin A.

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Animals Catalysis Hydrogen-Ion Concentration Hydrolysis Kinetics Pepsin A Peptides Substrate Specificity Swine Tyrosine Comparative Study Journal Article

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C A Auffret, A P Ryle. 1979-04-01. The catalytic activity of pig pepsin C towards small synthetic substrates.. https://doi.org/10.1042/bj1790239

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