REVERSAL OF PART OF THE ALDEHYDE DEHYDROGENASE REACTION PATHWAY DURING THE HYDROLYSIS OF AN ESTER

An aldehyde dehydrogenase from rabbit liver, a homogeneous protein on three distinct polyacrylamide-gel systems, has an associated 4-nitrophenyl esterase activity. At pH 7.0 in the presence of 80 micrometer-NADH and 800 micrometer-4-nitrophenyl acetate the enzyme produces NAD+ and a stoicheiometric amount of an aldehyde, as well as hydrolysing the ester. On this and other evidence it is proposed that ester hydrolysis occurs at the usual active site of the enzyme.