Four cDNA clones that were annotated in the database as encoding d-amino acid oxidase (DAAO) or d-aspartate oxidase (DASPO) were iso-lated by RT-PCR from Caenorhabditis elegans RNA. The proteins (Y69Ap, C47Ap, F18Ep, and F20Hp) encoded by the cloned cDNAs were expressed in Escherichia colias recombinant proteins with an N-terminal His-tag.