Accepted name: catechol 2,3-dioxygenase
Reaction: catechol + O2 = 2-hydroxymuconate-6-semialdehyde
Glossary: 2-hydroxymuconate-6-semialdehyde = (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate
Other name(s): 2,3-pyrocatechase; catechol 2,3-oxygenase; catechol oxygenase; metapyrocatechase; pyrocatechol 2,3-dioxygenase; xylE (gene name); catechol:oxygen 2,3-oxidoreductase (decyclizing)
Systematic name: catechol:oxygen 2,3-oxidoreductase (ring-opening)
Comments: Requires FeII. The enzyme initiates the meta-cleavage pathway of catechol degradation.
1.  Hayaishi, O. Direct oxygenation by O2, oxygenases. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Eds), The Enzymes, 2nd edn, vol. 8, Academic Press, New York, 1963, pp. 353–371.
2.  Kojima, Y., Itada, N. and Hayaishi, O. Metapyrocatechase: a new catechol-cleaving enzyme. J. Biol. Chem. 236 (1961) 2223–2228. [PMID: 13757654]
3.  Nozaki, M., Kagamiyama, H. and Hayaishi, O. Metapyrocatechase. I. Purification, crystallization and some properties. Biochem. Z. 338 (1963) 582–590. [PMID: 14087325]
4.  Nakai, C., Hori, K., Kagamiyama, H., Nakazawa, T. and Nozaki, M. Purification, subunit structure, and partial amino acid sequence of metapyrocatechase. J. Biol. Chem. 258 (1983) 2916–2922. [PMID: 6826545]
5.  Junker, F., Field, J.A., Bangerter, F., Ramsteiner, K., Kohler, H.-P., Joannou, C.L., Mason, J.R., Leisinger, T. and Cook, A.M. Oxygenation and spontaneous deamination of 2-aminobenzenesulphonic acid in Alcaligenes sp. strain O-1 with subsequent meta ring cleavage and spontaneous desulphonation to 2-hydroxymuconic acid. Biochem. J. 300 (1994) 429–436. [PMID: 8002948]
6.  Junker, F., Leisinger, T. and Cook, A.M. 3-Sulphocatechol 2,3-dioxygenase and other dioxygenases (EC and EC 1.14.12.-) in the degradative pathways of 2-aminobenzenesulphonic, benzenesulphonic and 4-toluenesulphonic acids in Alcaligenes sp. strain O-1. Microbiology 140 (1994) 1713–1722. [PMID: 8075807]
[EC created 1965 as EC, transferred 1972 to EC, modified 1999, modified 2013]
Accepted name: cysteine dioxygenase
Reaction: L-cysteine + O2 = 3-sulfinoalanine
Other name(s): cysteine oxidase
Systematic name: L-cysteine:oxygen oxidoreductase
Comments: Requires Fe2+ and NAD(P)H.
1.  Lombardini, J.B., Singer, T.P. and Boyer, P.D. Cystein oxygenase. II. Studies on the mechanism of the reaction with 18oxygen. J. Biol. Chem. 244 (1969) 1172–1175. [PMID: 5767301]
[EC created 1972, modified 1976]
Transferred entry: β-carotene 15,15′-dioxygenase. Now EC, β-carotene 15,15′-monooxygenase
[EC created 1972, deleted 2001]
Accepted name: caffeate 3,4-dioxygenase
Reaction: 3,4-dihydroxy-trans-cinnamate + O2 = 3-(2-carboxyethenyl)-cis,cis-muconate
Other name(s): 3,4-dihydroxy-trans-cinnamate:oxygen 3,4-oxidoreductase (decyclizing)
Systematic name: 3,4-dihydroxy-trans-cinnamate:oxygen 3,4-oxidoreductase (ring-opening)
1.  Seidman, M.M., Toms, A. and Wood, J.M. Influence of side-chain substituents on the position of cleavage of the benzene ring by Pseudomonas fluorescens. J. Bacteriol. 97 (1969) 1192–1197. [PMID: 5776526]
[EC created 1972]
Accepted name: 2,3-dihydroxyindole 2,3-dioxygenase
Reaction: 2,3-dihydroxyindole + O2 = anthranilate + CO2
Other name(s): 2,3-dihydroxyindole:oxygen 2,3-oxidoreductase (decyclizing)
Systematic name: 2,3-dihydroxyindole:oxygen 2,3-oxidoreductase (ring-opening)
1.  Fujioka, M. and Wada, H. The bacterial oxidation of indole. Biochim. Biophys. Acta 158 (1968) 70–78. [PMID: 5652436]
[EC created 1972]
Accepted name: quercetin 2,3-dioxygenase
Reaction: quercetin + O2 = 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoate + CO + H+
Other name(s): quercetinase; flavonol 2,4-oxygenase; quercetin:oxygen 2,3-oxidoreductase (decyclizing)
Systematic name: quercetin:oxygen 2,3-oxidoreductase (ring-opening)
Comments: The enzyme from Aspergillus sp. is a copper protein whereas that from Bacillus subtilis contains iron. Quercetin is a flavonol (5,7,3′,4′-tetrahydroxyflavonol).
1.  Oka, T. and Simpson, F.J. Quercetinase, a dioxygenase containing copper. Biochem. Biophys. Res. Commun. 43 (1971) 1–5. [PMID: 5579942]
2.  Steiner, R.A., Kalk, K.H. and Dijkstra, B.W. Anaerobic enzyme·substrate structures provide insight into the reaction mechanism of the copper-dependent quercetin 2,3-dioxygenase. Proc. Natl. Acad. Sci. USA 99 (2002) 16625–16630. [PMID: 12486225]
3.  Bowater, L., Fairhurst, S.A., Just, V.J. and Bornemann, S. Bacillus subtilis YxaG is a novel Fe-containing quercetin 2,3-dioxygenase. FEBS Lett. 557 (2004) 45–48. [PMID: 14741339]
[EC created 1972]
Accepted name: 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione 4,5-dioxygenase
Reaction: 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + O2 = 3-hydroxy-5,9,17-trioxo-4,5:9,10-disecoandrosta-1(10),2-dien-4-oate
Other name(s): steroid 4,5-dioxygenase; 3-alkylcatechol 2,3-dioxygenase; 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione:oxygen 4,5-oxidoreductase (decyclizing)
Systematic name: 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione:oxygen 4,5-oxidoreductase (ring-opening)
Comments: Requires Fe2+. Also acts on 3-isopropylcatechol and 3-tert-butyl-5-methylcatechol.
1.  Gibson, D.T., Wang, K.C., Sih, C.J. and Whitlock, J.H. Mechanisms of steroid oxidation by microorganisms. IX. On the mechanism of ring A cleavage in the degradation of 9,10-seco steroids by microorganisms. J. Biol. Chem. 241 (1966) 551–559. [PMID: 5908121]
[EC created 1972]
Accepted name: peptide-tryptophan 2,3-dioxygenase
Reaction: [protein]-L-tryptophan + O2 = [protein]-N-formyl-L-kynurenine
Glossary: N-formyl-L-kynurenine = (2S)-2-amino-4-[2-(formamido)phenyl]-4-oxobutanoic acid
Other name(s): pyrrolooxygenase; peptidyltryptophan 2,3-dioxygenase; tryptophan pyrrolooxygenase; [protein]-L-tryptophan:oxygen 2,3-oxidoreductase (decyclizing)
Systematic name: [protein]-L-tryptophan:oxygen 2,3-oxidoreductase (ring-opening)
Comments: Also acts on tryptophan.
1.  Frydman, R.B., Tomaro, M.L. and Frydman, B. Pyrrolooxygenase: its action on tryptophan-containing enzymes and peptides. Biochim. Biophys. Acta 284 (1972) 80–89. [PMID: 4403729]
2.  Camoretti-Mercado, B. and Frydman, R.B. Separation of tryptophan pyrrolooxygenase into three molecular forms. A study of their substrate specificities using tryptophyl-containing peptides and proteins. Eur. J. Biochem. 156 (1986) 317–325. [PMID: 3699018]
[EC created 1972, modified 2011]
Accepted name: 4-hydroxyphenylpyruvate dioxygenase
Reaction: 4-hydroxyphenylpyruvate + O2 = homogentisate + CO2
Other name(s): p-hydroxyphenylpyruvic hydroxylase; p-hydroxyphenylpyruvate hydroxylase; p-hydroxyphenylpyruvate oxidase; p-hydroxyphenylpyruvic oxidase; p-hydroxyphenylpyruvate dioxygenase; p-hydroxyphenylpyruvic acid hydroxylase; 4-hydroxyphenylpyruvic acid dioxygenase
Systematic name: 4-hydroxyphenylpyruvate:oxygen oxidoreductase (hydroxylating, decarboxylating)
Comments: The Pseudomonas enzyme contains one Fe3+ per mole of enzyme; the enzymes from other sources may contain essential iron or copper.
1.  Lindstedt, S. and Rundgren, M. Blue color, metal content, and substrate binding in 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. strain P. J. 874. J. Biol. Chem. 257 (1982) 11922–11931. [PMID: 7118918]
2.  Roche, P.A., Moorehead, T.J. and Hamilton, G.A. Purification and properties of hog liver 4-hydroxyphenylpyruvate dioxygenase. Arch. Biochem. Biophys. 216 (1982) 62–73. [PMID: 7103516]
[EC created 1961 as EC, transferred 1965 to EC, transferred 1972 to EC]
Accepted name: 2,3-dihydroxybenzoate 2,3-dioxygenase
Reaction: 2,3-dihydroxybenzoate + O2 = 2-carboxy-cis,cis-muconate
Other name(s): 2,3-dihydroxybenzoate 2,3-oxygenase; 2,3-dihydroxybenzoate:oxygen 2,3-oxidoreductase (decyclizing)
Systematic name: 2,3-dihydroxybenzoate:oxygen 2,3-oxidoreductase (ring-opening)
Comments: Also acts, more slowly, with 2,3-dihydroxy-4-methylbenzoate and 2,3-dihydroxy-4-isopropylbenzoate.
1.  La Du, B.N. and Zannoni, V.G. The tyrosine oxidation system of liver. III. Further studies on the oxidation of p-hydroxyphenylpyruvic acid. J. Biol. Chem. 219 (1956) 273–281. [PMID: 13295279]
2.  Sharma, H.K. and Vaidyanathan, C.S. A new mode of ring cleavage of 2,3-dihydroxybenzoic acid in Tecoma stans (L.). Partial purification and properties of 2,3-dihydroxybenzoate 2,3-oxygenase. Eur. J. Biochem. 56 (1975) 163–171. [PMID: 1175620]
[EC created 1978]
Accepted name: stizolobate synthase
Reaction: L-dopa + O2 = 4-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde
Glossary: L-dopa = 3,4-dihydroxy-L-phenylalanine
Systematic name: 3,4-dihydroxy-L-phenylalanine:oxygen 4,5-oxidoreductase (recyclizing)
Comments: The intermediate product undergoes ring closure and oxidation, with NAD(P)+ as acceptor, to stizolobic acid. The enzyme requires Zn2+.
1.  Saito, K. and Komamine, A. Biosynthesis of stizolobinic acid and stizolobic acid in higher plants. An enzyme system(s) catalyzing the conversion of dihydroxyphenylalanine into stizolobinic acid and stizolobic acid from etiolated seedlings of Stizolobium hassjoo. Eur. J. Biochem. 68 (1976) 237–243. [PMID: 9285]
2.  Saito, K. and Komamine, A. Biosynthesis of stizolobinic acid and stizolobic acid in higher plants. Eur. J. Biochem. 82 (1978) 385–392. [PMID: 624278]
[EC created 1978]

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