EC Explorer

1.14.13.118

valine N-monooxygenase

L-valine + 2 O₂ + 2 NADPH + 2 H⁺ = (E)-2-methylpropanal oxime + 2 NADP⁺ + CO₂ + 3 H₂O (overall reaction);;(1a) L-valine + O₂ + NADPH + H⁺ = N-hydroxy-L-valine + NADP⁺ + H₂O;;(1b) N-hydroxy-L-valine + O₂ + NADPH + H⁺ = N,N-dihydroxy-L-valine + NADP⁺ + H₂O;;(1c) N,N-dihydroxy-L-valine = (E)-2-methylpropanal oxime + CO₂ + H₂O

CYP79D1, CYP79D2

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

A heme-thiolate protein (P-450). This enzyme catalyses two successive N-hydroxylations of L-valine, the first committed steps in the biosynthesis of the cyanogenic glucoside linamarin in Manihot esculenta (cassava). The product of the two hydroxylations, N,N-dihydroxy-L-valine, 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-methylpropanal oxime, undergoes a spontaneous isomerization to the (Z) form. The enzyme can also accept L-isoleucine as substrate, with a lower activity. It is different from EC 1.14.13.117 (isoleucine N-monooxygenase), which prefers L-isoleucine.

created 2010, deleted 2017