The metabolism of D- and L- glutamic acid in the rat.

When DL-&ltMniC acid-2-V was administered to rats by intraperitoneal injection (l), conversion to succinate via a-ketoglutarate was the primary route of catabolism. However, when glutamate was injected into the cecum of rats, carbon 2 was converted to the methyl carbon of acetate (I). Glutamic acid administered by stomach tube was metabolized by both of the above mentioned pathways (1). The present report deals with the results of similar studies with Dand L-glutamic acid-2-V and DLand n-glutamic acid5-C4. The data suggest that (a) after intraperitoneal injection, L-glutamate is catabolized via a-ketoglutarate, whereas Dglutamate is converted to n-pyrrolidone carboxylic acid (2) ; (b) carbon 2 of both Dand L-glutamate is converted in the cecum to the methyl carbon of acetate, probably by the route described by Barker et al. (3-5) rather than via the Stickland reaction (6); and (c) both rat liver and kidney catalyze the conversion of n-glutamic acid to n-pyrrolidone carboxylic acid.