On the role of acetyl cyanide in the cyanide-induced acetylation of amino acids by enzymes of Clostridium kluyveri

Abstract

Evidence has been obtained indicating that acetyl cyanide is an intermediary in the HCN-dependent acetylation of amino acids by acetyl phosphate that is catalyzed by cell-free extracts of Clostridium kluyveri. Acetyl cyanide formation from acetyl phosphate requires coenzyme A (CoA) and at least two enzymes present in C. kluyveri. One enzyme, phosphotransacetylase, catalyzes the formation of acetyl CoA from acetyl phosphate and CoA: the other enzyme catalyzes a reaction between acetyl CoA and HCN to form acetyl cyanide. In the absence of a suitable acetyl acceptor, the acetyl cyanide undergoes almost instantaneous, non-enzymic hydrolysis, but in the presence of aliphatic amines it reacts preferentially and non-enzymically to produce the N-acetyl derivatives. At relatively high concentrations of reactants, thiolesters undergo non-enzymic cleavage by HCN to form acetyl cyanide. The characteristics of the enzymic and non-enzymic cyanolytic reactions have been studied.