Modulation of the catalytic properties of alpha-chymotrypsin by chemical modification at Tyr 146.

alpha--Chymotrypsin was modified with three different diazonium salts derived from D--phenylalanine. All three reagents react selectively with tyrosine 146 on the surface of the enzyme. The spectral and enzymatic properties of the azochymotrypsins are characteristic for each of the proteins. Dependent on the structure of the reagent employed for modification, the activity towards rho-nitroanilide substrate can be higher or about the same as that of the native enzyme.