The Enzyme Database

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Accepted name: tryptophan N-monooxygenase
Reaction: L-tryptophan + 2 [reduced NADPH—hemoprotein reductase] + 2 O2 = (E)-indol-3-ylacetaldoxime + 2 [oxidized NADPH—hemoprotein reductase] + CO2 + 3 H2O (overall reaction)
(1a) L-tryptophan + [reduced NADPH—hemoprotein reductase] + O2 = N-hydroxy-L-tryptophan + [oxidized NADPH—hemoprotein reductase] + H2O
(1b) N-hydroxy-L-tryptophan + [reduced NADPH—hemoprotein reductase] + O2 = N,N-dihydroxy-L-tryptophan + [oxidized NADPH—hemoprotein reductase] + H2O
(1c) N,N-dihydroxy-L-tryptophan = (E)-indol-3-ylacetaldoxime + CO2 + H2O
Other name(s): tryptophan N-hydroxylase; CYP79B1; CYP79B2; CYP79B3
Systematic name: L-tryptophan,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (N-hydroxylating)
Comments: A cytochrome P-450 (heme-thiolate) protein from the plant Arabidopsis thaliana. This enzyme catalyses two successive N-hydroxylations of L-tryptophan, the first steps in the biosynthesis of both auxin and the indole alkaloid phytoalexin camalexin. The product of the two hydroxylations, N,N-dihydroxy-L-tryptophan, is extremely labile and dehydrates spontaneously. The dehydrated product is then subject to a decarboxylation that produces an oxime. It is still not known whether the decarboxylation is spontaneous or catalysed by the enzyme.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
1.  Mikkelsen, M.D., Hansen, C.H., Wittstock, U. and Halkier, B.A. Cytochrome P450 CYP79B2 from Arabidopsis catalyzes the conversion of tryptophan to indole-3-acetaldoxime, a precursor of indole glucosinolates and indole-3-acetic acid. J. Biol. Chem. 275 (2000) 33712–33717. [DOI] [PMID: 10922360]
2.  Hull, A.K., Vij, R. and Celenza, J.L. Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis. Proc. Natl. Acad. Sci. USA 97 (2000) 2379–2384. [DOI] [PMID: 10681464]
3.  Zhao, Y., Hull, A.K., Gupta, N.R., Goss, K.A., Alonso, J., Ecker, J.R., Normanly, J., Chory, J. and Celenza, J.L. Trp-dependent auxin biosynthesis in Arabidopsis: involvement of cytochrome P450s CYP79B2 and CYP79B3. Genes Dev. 16 (2002) 3100–3112. [DOI] [PMID: 12464638]
4.  Naur, P., Hansen, C.H., Bak, S., Hansen, B.G., Jensen, N.B., Nielsen, H.L. and Halkier, B.A. CYP79B1 from Sinapis alba converts tryptophan to indole-3-acetaldoxime. Arch. Biochem. Biophys. 409 (2003) 235–241. [DOI] [PMID: 12464264]
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