O aminophenol oxidase

O-aminophenol oxidase (EC 1.10.3.4, isophenoxazine synthase, o-aminophenol:O₂ oxidoreductase, 2-aminophenol:O₂ oxidoreductase, GriF) is an enzyme with systematic name 2-aminophenol:oxygen oxidoreductase. This enzyme catalyses the following chemical reaction

2 2-aminophenol + O₂ + acceptor ⇌ 2-aminophenoxazin-3-one + reduced acceptor + 2 H₂O (overall reaction) (1a) 2 2-aminophenol + O₂ ⇌ 2 6-iminocyclohexa-2,4-dienone + 2 H₂O (1b) 2 6-iminocyclohexa-2,4-dienone + acceptor ⇌ 2-aminophenoxazin-3-one + reduced acceptor (spontaneous)

O-aminophenol oxidase is a flavoprotein.