Figure 2
From: N-Methyl-D-aspartic Acid (NMDA) in the nervous system of the amphioxus Branchiostoma lanceolatum
HPLC analysis of NMDA through the determination of CH 3 NH 2 of the nerve cord after purification with OPA. A) The figure shows a typical pattern of free amino acids from B. lanceolatum nerve cord before purification by OPA treatment. B) The same sample after purification with OPA, which eliminates all the amino acids (or almost all) except NMDA. Note that it is not possible to see the NMDA in this graphic because it does not react with OPA-mercaptoethanol, that is the reagent used for the determination of free amino acids at HPLC. C) The same sample as B, but after treatment with D-AspO. In this case, the D-AspO oxidizes NMDA producing the CH3NH2 which reacts with OPA-mercaptoethanol to give a well-defined sharp peak at the end of the chromatogram at retention time 11.8–12.0 min.