This subfamily contains bacterial and eukaryotic cupin domains of proteins homologous to oxalate decarboxylase (OxDC; EC 4.1.1.2) such as MSMEG_2254, a putative OxDC from Mycobacterium smegmatis. OxDC is a manganese-dependent bicupin that catalyzes the conversion of oxalate to formate and carbon dioxide, utilizing dioxygen as a cofactor. It is evolutionarily related to oxalate oxidase (OxOx or germin; EC 1.2.3.4) which, in contrast, converts oxalate and dioxygen to carbon dioxide and hydrogen peroxide. OxDC is classified as a bicupin because it contains two cupin folds with each domain containing one manganese binding site, with four manganese binding residues (three histidines and one glutamate) conserved as well as a number of hydrophobic residues.
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