Administration of D-aspartate increases D-aspartate oxidase activity in mouse liver

Oral administration of D-aspartate to mice for 2 weeks by addition of the amino acid to drinking water produced a nearly 4-fold increase in liver D-aspartate oxidase (EC 1.4.3.1) activity, whereas no increase was induced by L-aspartate administered in the same way. Administration of D-aspartate also produced a small significant increase in the kidney enzyme activity, but L-aspartate administration increased the activity as well. The enzyme activity in the brain and muscle was not affected by administration of either D- or L-aspartate. Intraperitoneal administration of D-aspartate increased the enzyme activity only in the liver, and other compounds tested, including D-glutamate and D-alanine, could not replace D-aspartate. The results indicate a specific relationship between D-aspartate and D-aspartate oxidase and suggest that the amino acid is, in fact, a physiological substrate of the enzyme.