Salt Effects on the Properties of α‐Chymotrypsin: I. Effects on the Enzymic Activity of Chymotrypsin

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Abstract
The effects of salts on the activity of α‐chymotrypsin have been studied in detail. In high salt concentration (2 M NaCl) the rate of the enzyme‐catalyzed hydrolysis reactions increased compared to that in low salt. Substrates displayed lower Km and higher kcat values, and with irreversible inhibitors the reaction rate rather than binding was affected in high salt. The activity of chymotrypsin towards specific substrates of trypsin was enhanced by high salt to a larger extent than the activity towards its own specific substrates, and polylysine became a good substrate. Apolar competitive inhibitors exhibited tighter binding in high salt. Analysis of the kinetic data indicated that the acylation step was increased much more than the deacylation step. The effectiveness of different salts in general followed the Hofmeister series. High‐salt‐induced conformational change is considered as a factor affecting the enzymic reaction kinetics.