D-Amino-Acid Oxidase (DAO) belongs to the DAMOX/DASOX family. DAO is a peroxisomal enzyme which founctions as a homodimer to oxidizes D-amino acids to the corresponding imino acids, producing ammonia and hydrogen peroxide. D-amino-acid oxidase regulates the level of the neuromodulator D-serine in the brain, has a high activity towards D-DOPA and contributes to dopamine synthesis. D-amino-acid oxidase could act as a detoxifying agent which removes D-amino acids accumulated during aging. It also acts on a variety of D-amino acids with a preference for those having small hydrophobic side chains followed by those bearing polar, aromatic, and basic groups.