Identification of D-serine via capillary electrophoresis. (A) Electropherogram showing the separation of D-serine (D-ser), from a series of amino acid standards; Gamma-aminobutyric acid (GABA), Taurine (Tau), Glycine (Gly), L-serine (L-ser), α-aminoadipic acid (AAA), and Glutamate (Glu). Treatment with D-serine deaminase (DsDa) (50 ug/ml, 20 min) specifically eliminated D-serine (dotted trace). (B) Separation of amino acids from mouse retina extracellular media, with L-serine and D-serine expanded. D-serine was completely eliminated following DsDa incubation.