NUCLEOPHILE SPECIFICITY IN TRYPSIN-CATALYZED ACYL TRANSFER USING NONSPECIFIC ACYL DONORS

The S'-subsite specificity of trypsin has been studied by comparing th e non-specific acyl donors Mal-Phe-OCam (Mal = maleyl, OCam = carboxam idomethyl ester), Mal-Gly-Phe-OCam and Mal-Phe-OMe (OMe = methyl eater ) with the specific substrate Bz-Arg-OEt (Bz = benzoyl, OEt = ethyl ea ter). Various nucleophilic amino components were chosen to determine S '(1)-P'(1) interactions depending on the acyl donor used. The data obt ained underline that there are no significant differences in the nucle ophile specificity for specific and non-specific acyl donors, but with the latter a slightly better acceptance of the nucleophiles was found . Independent of the acyl donor used, a preference for methionine and arginine-in the S'(1)-subsite of trypsin could be established, The res ults provide evidence that the binding site of the non-specific substr ates in the active site of trypsin is not different to that of Bz-Arg- OEt.