Dglutamic

Dglutamic acid, commonly written as D-glutamic acid or D-Glu, is the D-enantiomer of the amino acid glutamic acid. It is one of the two mirror-image forms of glutamic acid, differing from the biologically dominant L-form. As an α-amino acid, it has the same chemical formula as L-glutamic acid but a different configuration at the alpha carbon; at physiological pH it exists primarily as a zwitterion.

Natural occurrence and function: D-glutamate is found mainly in bacteria, where it is incorporated into the peptidoglycan layer of the cell wall. In many Gram-positive bacteria, the stem peptide includes D-Glu as part of the cross-linking region, contributing to cell-wall rigidity and resistance to osmotic stress. D-glutamate can be produced from L-glutamate by racemization via the enzyme glutamate racemase (MurI); this reaction is essential for peptidoglycan synthesis in numerous bacterial species and is not a common feature of animal metabolism.

Humans and metabolism: Humans do not use D-glutamate in protein synthesis, which relies on L-amino acids. D-amino acids, including D-glutamate, are metabolized more slowly in humans and are processed by specialized enzymes such as D-amino acid oxidases in certain tissues. D-glutamate may occur in trace amounts in the gut microbiome and can be present in some research reagents or pharmaceutical preparations.

Industrial and medical relevance: D-glutamic acid serves as a chiral building block in chemical synthesis and in the development of compounds that target bacterial cell-wall synthesis. Enzymes involved in D-glu racemization or D-Ala-D-Ala ligation are of interest as potential antibiotic targets, reflecting the role of D-glutamate in bacterial physiology.