Almost all animals and plants synthesize their own vitamin C, but humans cannot because the gene for this enzyme is defective (Pseudogene ΨGULO).
NADPH oxidase | oxidase | Cytochrome c oxidase | cytochrome c oxidase | Oxidase | Monoamine oxidase | cytochrome ''c'' oxidase | monoamine oxidase | Reticuline oxidase | Monoamine oxidase B | L-gulonolactone oxidase | D-amino acid oxidase | Cytochrome c oxidase subunit I |