An unusual stable adduct in the reaction of pyruvate with papain Chemically modiied by 3-acetyl pyridinium and quinolinium derivatives

Abstract

We have previously shown that electrophilic carbonyl compounds including ethyl pyruvate are slowly reduced by 3-acetyl-1,4-dihydropyridines attached to the active site thiol group of papain 1. The mechanism of this reaction has been investigated using sodium 2-[ 13C]-pyruvate as substrate. In contrast, reduction did not occur but the formation of an unexpected stable adduct assigned to the enol of the heterocyclic prosthetic groups to C-2 of pyruvate was observed.