O-aminophenol oxidase

UniProtKB accession:  Q53692

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UniProtKB description:  Could be involved in the spore pigmentation and melanin production. Catalyzes the oxidative coupling of 2-aminophenols to form the 2-aminophenoxazinone chromophore. 2-aminophenoxazinone synthesis proceeds via a sequence of three consecutive 2-electron aminophenol oxidations. First, the o-aminophenol is oxidized by two electrons to the quinone imine, which then conjugates to a second o-aminophenol molecule while still bound to the enzyme. This product is further oxidized by two electrons to give rise to the p-quinone imine. The last two steps of the reaction, another conjugation to generate the tricyclic structure and a final two-electron oxidation to yield the 2-aminophenoxazinone product, are thought to be non-enzymatic. It can also uuse 3-hydroxyanthranilic acid (HAA), 4-methyl-3-hydroxyanthranilic acid (MHA), 3,4-dihydroxy-L-phenylalanine (L-DOPA), ferrocyanide and thiophenol as substrates.