Study of the solid-state enzyme reactions. 3. Irreversible inactivation of α-chymotrypsin by benzylsulfonyl fluoride

Yu. I. Khurgin, E. Yu. Maksareva

N. D. Zelinsky Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow

Abstract: In solvent-free solid mixture of α-chymotrypsin and benzylsulfonyl fluoride (PMSF) the irreversible inactivation of the ensyme's activity takes place when hydration (H) of the protein molecule exceeds a certain critical value Hcrit=127 moles of H2O per mole of α-chymotrypsin. This value is approximately equal to the Hcrit obtained for the solid-state chymotrypsin-catalysed hydrolysis of a substrate, N-succinyl-L-phenylalanine p-nitroanilide. The shape of the inactivation isotherm confirms the phase transition at Hcrit and demonstrates that the main mass of the protein (up to 75%) is activable, but heterogeneous with respect to the hydration level necessary for switching on the catalytic activity of α-chymotrypsin.

Russian Journal of Bioorganic Chemistry 1991, 17 (1):76-80

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