D-amino acid oxidase (<db_xref db="EC" dbkey="1.4.3.3"/>) (DAMOX or DAO) is an FAD flavoenzyme that catalyzes the oxidation of neutral and basic D-amino acids into their corresponding keto acids. DAOs have been characterised and sequenced in fungi and vertebrates where they are known to be located in the peroxisomes. D-aspartate oxidase (<db_xref db="EC" dbkey="1.4.3.1"/>) (DASOX) [<cite idref="PUB00002712"/>] is an enzyme, structurally related to DAO, which catalyzes the same reaction but is active only toward dicarboxylic D-amino acids. In DAO, a conserved histidine has been shown [<cite idref="PUB00002345"/>] to be important for the enzyme's catalytic activity. D-amino acid oxidase, conserved site