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Oxalate oxidase (germin), cupin domain Oxalate oxidase (OxOx, also known as germin; EC 1.2.3.4) catalyzes the manganese-dependent oxidative decarboxylation of oxalate to carbon dioxide and hydrogen peroxide (H2O2). It is widespread in fungi and various plant tissues and may play a role in plant signaling and defense. This enzyme has been employed in a widely used assay for detecting urinary oxalate levels. Also, the gene encoding OxOx from barley roots has been expressed in oilseed rape in order to provide a defense against externally supplied oxalic acid. In germin, the predominant protein produced during the early phase of wheat germination, it is believed that H2O2 production is employed as a defense mechanism in response to infection by pathogens. Germin is also a marker of growth onset in cell walls in germinating cereals. The H2O2 produced by OxOx, together with the Ca2+ released by degradation of calcium oxalate, are thought to mediate cell wall cross-linking at high concentrations. Proteins in this family belong to the cupin superfamily with a conserved "jelly roll-like" beta-barrel fold capable of homodimerization. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",