Fluorimetric assay for D-amino acid oxidase activity in rat brain homogenate by using D-kynurenine as a substrate.

An easy fluorimetric assay for measuring D-amino acid oxidase (DAAO) activity by using one of the D-amino acids--D-kynurenine (D-KYN)--as a substrate was applied to assess DAAO activity in the cerebrum, cerebellum, and brainstem of Sprague-Dawley (SD) male rats. In this assay, DAAO produces kynurenic acid (KYNA) from D-KYN, and the fluorescence originating from KYNA can then be used to evaluate DAAO activity. Here, pellet fractions obtained by centrifugation of brain homogenates were allowed to react enzymatically with D-KYN.