HPLC methods for determination of d-aspartate and n-methyl-d-aspartate

Abstract

d-Amino acids are stereoisomers or optical isomers of naturally occurring l-amino acids and thus possess the same chemical structure, but may differ in their biological/physiological properties. Until a half century ago, d-amino acids had been considered to be unnatural substances found only in microorganisms. However, improvements in analytical instruments and methods have revealed that d-amino acids are present in invertebrates and vertebrates, including humans, and that they possess important physiological functions. d-Aspartate (d-Asp) and its methylated form N-methyl-d-aspartate (NMDA) possess neuroendocrine properties in many species. Several methods have been developed for determination of d-and l-enantiomers of amino acids by high performance liquid chromatography (HPLC). We report here improved HPLC methods for the specific determination of d-Asp and NMDA in biological tissues.