DECARBOXYLATION OF 2-AMINOMALONIC ACID BY SERINE HYDROXYMETHYLTRANSFERASE IS, IN FACT, A STEREOSPECIFIC PROCESS

Contrary to the results of an earlier study, 2-aminomalonic acid is de carboxylated stereospecifically by serine hydroxymethyltransferase. Th e newly introduced hydrogen occupies the 2-pro-S position of the glyci ne product and, by analogy to studies using 2-amino-2-methylmalonic ac id as the substrate (preceding paper in this issue), it is expected th at the pro-R carboxy group is lost during the reaction. A study of the rates of C(alpha)-H hydrogen exchange for 2-aminomalonic acid with so lvent hydrogen from the aqueous buffer indicates that hydrogen exchang e and racemisation would have complicated the analysis of the results in the earlier study.