D-amino acid oxidase (DAAO; also DAO, OXDA, DAMOX) is a peroxisomal enzyme containing FAD as cofactor that is expressed in a wide range of species from yeasts to human. It is not present in plants or in bacteria which instead use D-amino acid dehydrogenase. Its function is to oxidize D-amino acids to the corresponding imino acids, producing ammonia and hydrogen peroxide. DAAO is a candidate susceptibility gene and together with G72 may play a role in the glutamatergic mechanisms of schizophrenia. Risperidone and sodium benzoate are inhibitors of DAAO.