Transamination of D-amino acids by Bacillus subtilis.

A wide variety of transaminase active on L-amino acids has been demonstrated in microorganisms (Feldman and Gunsalus, 1950; Fincham, 1951), mammalian tissues (Cammarata and Cohen, 1950; Rowsell, 1951), and plants (Wilson et al., 1954). Cohen (1939, 1940) did not find transaminase activity with any of several D-amino acids when he tested minced pigeon breast muscle or purified enzyme preparations although other workers (Euler et al., 1939; Braunstein and Azarkh, 1939) reported that certain D-amino acids were slightly active when tested with mammalian tissue preparations. It has been suggested (Herbst, 1944) that the reports which ascribed activity to D-amino acids may have been in error because of inadequate analytical methods. Stumpf (1951) reported that D-alanine behaved as an active amino donor in reaction mixtures containing a-ketoglutaric acid and enzyme preparations from plants. It was not clear, however, whether D-alanine participated directly in transamination or whether it contributed the amino group in some indirect manner. In studies on the mechanisms of synthesis of D-glutamic acid and glutamyl polypeptide by Bacillus subtilis, we observed that sonic extracts of this organism catalyzed a series of transamination reactions involving D-amino acids. The results of some of our studies on these D-amino acid transaminations are presented here.