SYNTHESIS OF AMIDRAZONES USING AN ENGINEERED PAPAIN NITRILE HYDRATASE

To demonstrate the usefulness of an engineered papain nitrile hydratas e as a biocatalyst, a peptide amidrazone mas prepared by incubation of the nitrile MeOCO-Phe-Ala-nitrile with the Gln(19)Glu papain mutant i n the presence of salicylic hydrazide as a nucleophile, The amidrazone results from nucleophilic attack by salicylic hydrazide at the imino carbon of the thioimidate adduct formed between the enzyme and the pep tide nitrile substrate, Compared to wild-type enzyme, the engineered n itrile hydratase causes a better than 4000-fold increase in the rate o f amidrazone formation and yields a product of much higher purity. The advantages over other nitrile-hydrolyzing enzymes and current limitat ions of the papain nitrile hydratase are discussed. Published by Elsev ier on behalf of the Federation of European Biochemical Societies.