Reaction: (1) (E)-indol-3-ylacetaldehyde oxime + [reduced NADPH—hemoprotein reductase] + glutathione + O2 = S-[(E)-N-hydroxy(indol-3-yl)acetimidoyl]-L-glutathione + [oxidized NADPH—hemoprotein reductase] + 2 H2O (overall reaction)
(1a) (E)-indol-3-ylacetaldehyde oxime + [reduced NADPH—hemoprotein reductase] + O2 = 1-(1H-indol-3-yl)-2-aci-nitroethane + [oxidized NADPH—hemoprotein reductase] + H2O
(1b) 1-(1H-indol-3-yl)-2-aci-nitroethane + glutathione = S-[(E)-N-hydroxy(indol-3-yl)acetimidoyl]-L-glutathione + H2O (spontaneous)
(2) (E)-phenylacetaldehyde oxime + [reduced NADPH—hemoprotein reductase] + glutathione + O2 = S-[(Z)-N-hydroxy(phenyl)acetimidoyl]-L-glutathione + [oxidized NADPH—hemoprotein reductase] + 2 H2O (overall reaction)
(2a) (E)-phenylacetaldehyde oxime + [reduced NADPH—hemoprotein reductase] + O2 = 1-aci-nitro-2-phenylethane + [oxidized NADPH—hemoprotein reductase] + H2O
(2b) 1-aci-nitro-2-phenylethane + glutathione = S-[(Z)-N-hydroxy(phenyl)acetimidoyl]-L-glutathione + H2O (spontaneous)
Other name(s): CYP83B1 (gene name)
Systematic name: (E)-indol-3-ylacetaldoxime,[reduced NADPH—hemoprotein reductase],glutathione:oxygen oxidoreductase (oxime-hydroxylating)
Comments: This cytochrome P-450 (heme thiolate) enzyme is involved in the biosynthesis of glucosinolates in plants. The enzyme catalyses the N-hydroxylation of aromatic aldoximes derived from L-tryptophan, L-phenylalanine, and L-tyrosine, 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 glutathione, the enzyme is suicidal, probably due to interaction of the reactive aci-nitro compound with catalytic residues in the active site.
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. Geu-Flores, F., Møldrup, M.E., Böttcher, C., Olsen, C.E., Scheel, D. and Halkier, B.A. Cytosolic γ-glutamyl peptidases process glutathione conjugates in the biosynthesis of glucosinolates and camalexin in Arabidopsis. Plant Cell 23 (2011) 2456-2469. [PMID: 21712415]