OXALOACETATE DECARBOXYLASE FROM COD . MECHANISM OF ACTION AND STEREOSELECTIVE REDUCTION OF PYRUVATE BY BOROHYDRIDE

Sodium borohydride has no effect upon the activity of the enzyme, oxaloacetate decarboxylase from cod, regardless of whether substrate is present or absent, or whether pyruvate (the reaction product) is present or absent. However, the reduction of pyruvate by borohydride in the presence of manganous ions and enzyme leads to the formation of an excess of D-lactate, as shown by the dispersion curve for optical activity and by specific enzyme assays with D- and L-lactate dehydrogenases. The enzymic catalysis of borohydride reduction depends upon the presence of metal ions and does not occur in the presence of EDTA. These facts are consistent with the hypothesis that reduction and decarboxylation occur by way of a metal ion-enzyme- substrate complex analogous to that previously suggested for relevant model systems. © 1968, American Chemical Society. All rights reserved.