D-glutamic acid, an enantiomer of L- glutamic acid, is widely used in pharmaceuticals and foods.
Various d-amino acids, such as D-serine, D-aspartic acid (D-Asp), and D-glutamic acid (D-Glu) are widely found in mammals including human beings and they are now thought to be the candidates of novel physiologically active substances and/or biomarkers[1]. D-[Asp/Glu] (4 mg/mL) inhibits IgE binding (75%) to peanuts while D-Glu, D-Asp has no inhibitory effect. IgE is specific for D-[Asp/Glu] and may have the potential for removing IgE or reducing IgE binding to peanut allergens[2].
D-glutamic acid is currently paid attention as a modulator of neuronal transmission and hormonal secretion. It is metabolized only by D-aspartate oxidase in mammals[1]. After intraperitoneal injection, L-glutamate is catabolized via a-ketoglutarate, whereas D-glutamate is converted to n-pyrrolidone carboxylic acid. Carbon 2 of both D- and L-glutamate is converted in the cecum to the methyl carbon of acetate. Both rat liver and kidney catalyze the conversion of D-glutamic acid to n-pyrrolidone carboxylic acid[3].
References:
[1]. Han H, et al. Changes in D-aspartic acid and D-glutamic acid levels in the tissues and physiological fluids of mice with various D-aspartate oxidase activities. J Pharm Biomed Anal. 2015 Dec 10;116:47-52.
[2]. Chung SY, et al. IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids. Food Chem. 2015 Jan 1;166:248-53.
[3]. Wilson W, et al. The metabolism of D- and L- glutamic acid in the rat. J Biol Chem. 1961 Feb;236:365-9.