IUBMB Enzyme Nomenclature


Accepted name: o-aminophenol oxidase

Reaction: 4 2-aminophenol + 3 O2 = 2 2-aminophenoxazin-3-one + 6 H2O

For diagram click here.

Glossary: 2-aminophenoxazin-3-one = isophenoxazine

Other name(s): isophenoxazine synthase; o-aminophenol:O2 oxidoreductase; 2-aminophenol:O2 oxidoreductase

Systematic name: 2-aminophenol:oxygen oxidoreductase

Comments: A flavoprotein which catalyses a 6-electron oxidation. The enzyme from the plant Tecoma stans requires Mn2+ and FAD [1] whereas the fungus Pycnoporus coccineus requires Mn2+ and riboflavin 5′-phosphate [2], the bacteria Streptomyces antibioticus requires Cu2+ [4] and the plant Bauhenia monandra does not require any co-factors [3].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 9013-85-8


1. Nair, P.M. and Vaidynathan, C.S. Isophenoxazine synthase. Biochim. Biophys. Acta 81 (1964) 507-516.

2. Nair, P.M. and Vining, L.C. Isophenoxazine synthase apoenzyme from Pycnoporus coccineus. Biochim. Biophys. Acta 96 (1965) 318-327. [PMID: 14298835]

3. Rao, P.V.S. and Vaidyanathan, C.S. Studies on the metabolism of o-aminophenol. Purification and properties of isophenoxazine synthase from Bauhenia monandra. Arch. Biochem. Biophys. 118 (1967) 388-394. [PMID: 4166439]

4. Barry, C.E., 3rd, Nayar, P.G. and Begley, T.P. Phenoxazinone synthase: mechanism for the formation of the phenoxazinone chromophore of actinomycin. Biochemistry 28 (1989) 6323-6333. [PMID: 2477054]

[EC created 1972, modified 2006]

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