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.
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. [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. [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. [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. [PMID: 12464264]
[EC created 2011 as EC, transferred 2018 to EC]