Decarboxylation of 2-aminomalonic acid by serine hydroxymethyltransferase is, in fact, a stereospecific process

Abstract

Contrary to the results of an earlier study, 2-aminomalonic acid is decarboxylated stereospecifically by serine hydroxymethyltransferase. The newly introduced hydrogen occupies the 2-pro-S position of the glycine product and, by analogy to studies using 2-amino-2-methylmalonic acid as the substrate (preceding paper in this issue), it is expected that the pro-R carboxy group is lost during the reaction. A study of the rates of C^α–H hydrogen exchange for 2-aminomalonic acid with solvent hydrogen from the aqueous buffer indicates that hydrogen exchange and racemisation would have complicated the analysis of the results in the earlier study.