Oxalate oxidase (OXO) catalyses the conversion of oxalate and dioxygen to hydrogen peroxide and carbon dioxide. The enzyme is widespread in nature but is most abundant in higher plant tissues, particularly germinating seeds. It is a member of a functionally diverse superfamily known at the cupins or double stranded β-helix proteins containing a mononuclear manganese centre in each subunit. The mechanism for OXO remains unclear. It is closely related to the bicupin oxalate decarboxylase which also contains manganese but produces carbon dioxide and formate.
Defined by 9 residues: ASN:A-75VAL:A-77ASN:A-85HIS:A-88HIS:A-90GLU:A-95HIS:A-137GLN:A-139MET:A-149