D-Glutamic acid 5-methyl ester is a protected form of D-Glutamic acid (G596965). D-Glutamic acid is an unnatural isomer of L-Glutamic acid (G596960), and is found in bacterial cell wall peptidoglycan of gram-positive and gram-negative bacteria. D-Glutamic acid also occurs as poly-gamma-Glutamic acid, which is a weak immunogen but is capable of acting as a hapten (a small molecule that induces the production of antibodies, as well as binding to them).