isoleucine N-monooxygenase;
CYP79D3;
CYP79D4

Oxidoreductases;
Acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2;
With NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor

L-isoleucine,NADPH:oxygen oxidoreductase (N-hydroxylating)

L-isoleucine + 2 O2 + 2 NADPH + 2 H+ = (E)-2-methylbutanal oxime + 2 NADP+ + CO2 + 3 H2O (overall reaction) [RN:R09403];
(1a) L-isoleucine + O2 + NADPH + H+ = N-hydroxy-L-isoleucine + NADP+ + H2O [RN:R10027];
(1b) N-hydroxy-L-isoleucine + O2 + NADPH + H+ = N,N-dihydroxy-L-isoleucine + NADP+ + H2O [RN:R10028];
(1c) N,N-dihydroxy-L-isoleucine = (E)-2-methylbutanal oxime + CO2 + H2O (spontaneous) [RN:R10029]

R09403 R10027 R10028 R10029;
(other) R10031 R10032 R10033

L-isoleucine [CPD:C00407];
O2 [CPD:C00007];
NADPH [CPD:C00005];
H+ [CPD:C00080];
N-hydroxy-L-isoleucine [CPD:C20310];
N,N-dihydroxy-L-isoleucine [CPD:C20311]

A heme-thiolate protein (P-450). This enzyme catalyses two successive N-hydroxylations of L-isoleucine, the first committed steps in the biosynthesis of the cyanogenic glucoside lotaustralin in the plant Lotus japonicus. The product of the two hydroxylations, N,N-dihydroxy-L-isoleucine, is extremely labile and dehydrates spontaneously. The dehydrated product is then subject to a decarboxylation that produces the oxime. It is still not known whether the decarboxylation is spontaneous or catalysed by the enzyme. The product, (E)-2-methylbutanal oxime, undergoes a spontaneous isomerization to the (Z) form. The enzyme can also accept L-valine as substrate, with a lower activity. It is different from EC 1.14.13.118 (valine N-monooxygenase), which prefers L-valine.

1  [PMID:10636899]

Andersen MD, Busk PK, Svendsen I, Moller BL

Cytochromes P-450 from cassava (Manihot esculenta Crantz) catalyzing the first steps in the biosynthesis of the cyanogenic glucosides linamarin and lotaustralin. Cloning, functional expression in Pichia pastoris, and substrate specificity of the isolated recombinant enzymes.

J. Biol. Chem. 275 (2000) 1966-75.

2  [PMID:15122013]

Forslund K, Morant M, Jorgensen B, Olsen CE, Asamizu E, Sato S, Tabata S, Bak S

Biosynthesis of the nitrile glucosides rhodiocyanoside A and D and the cyanogenic glucosides lotaustralin and linamarin in Lotus japonicus.

Plant. Physiol. 135 (2004) 71-84.