Reaction: an (E)-ω-(methylsulfanyl)alkanal oxime + O2 + glutathione + [reduced NADPH—hemoprotein reductase] = an (E)-1-(glutathione-S-yl)-ω-(methylsulfanyl)alkylhydroximate + 2 H2O + [oxidized NADPH—hemoprotein reductase] (overall reaction)
(1a) an (E)-ω-(methylsulfanyl)alkanal oxime + O2 + [reduced NADPH—hemoprotein reductase] = a 1-aci-nitro-ω-(methylsulfanyl)alkane + H2O + [oxidized NADPH—hemoprotein reductase]
(1b) a 1-aci-nitro-ω-(methylsulfanyl)alkane + glutathione = an (E)-1-(glutathione-S-yl)-ω-(methylsulfanyl)alkylhydroximate + H2O
Glossary: a 1-(methylsulfanyl)-4-aci-nitroalkane = a hydroxyoxo-λ5-azanylidene-ω-(methylsulfanyl)alkane
Other name(s): CYP83A1 (gene name); (methylthio)alkanaldoxime N-monooxygenase; (E)-ω-(methylthio)alkananaldoxime,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (N-hydroxylating)
Systematic name: (E)-ω-(methylsulfanyl)alkananaldoxime,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (N-hydroxylating)
Comments: This cytochrome P-450 (heme thiolate) enzyme is involved in the biosynthesis of glucosinolates in plants. The enzyme catalyses an N-hydroxylation of the E isomer of ω-(methylsulfanyl)aldoximes, forming an aci-nitro intermediate that reacts non-enzymically with glutathione to produce an N-alkyl-thiohydroximate adduct, the committed precursor of glucosinolates. In the absence of a thiol compound, the enzyme is suicidal, probably due to interaction of the reactive aci-nitro intermediate with active site residues.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Bak, S., Tax, F.E., Feldmann, K.A., Galbraith, D.W. and Feyereisen, R. CYP83B1, a cytochrome P450 at the metabolic branch point in auxin and indole glucosinolate biosynthesis in Arabidopsis. Plant Cell 13 (2001) 101-111. [PMID: 11158532]
2. Naur, P., Petersen, B.L., Mikkelsen, M.D., Bak, S., Rasmussen, H., Olsen, C.E. and Halkier, B.A. CYP83A1 and CYP83B1, two nonredundant cytochrome P450 enzymes metabolizing oximes in the biosynthesis of glucosinolates in Arabidopsis. Plant Physiol. 133 (2003) 63-72. [PMID: 12970475]
3. Clausen, M., Kannangara, R.M., Olsen, C.E., Blomstedt, C.K., Gleadow, R.M., Jørgensen, K., Bak, S., Motawie, M.S. and Møller, B.L. The bifurcation of the cyanogenic glucoside and glucosinolate biosynthetic pathways. Plant J. 84 (2015) 558-573. [PMID: 26361733]