|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions → Composite Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 188.8.131.52
Enzymes and Genes:
valine N-monooxygenase (oxime forming) : CYP79D1 ( Manihot esculenta )
valine N-monooxygenase (oxime forming) : CYP79D2 ( Manihot esculenta )
valine N-monooxygenase (oxime forming) : CYP79D3 ( Lotus japonicus )
isoleucine N-monooxygenase (oxime forming) : CYP79D4 ( Lotus japonicus )
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Most BioCyc compounds have been protonated to a reference pH value of 7.3, and some reactions have been computationally balanced for hydrogen by adding free protons. Please see the PGDB Concepts Guide for more information.
Mass balance status: Balanced.
Enzyme Commission Primary Name: valine N-monooxygenase
Enzyme Commission Synonyms: CYP79D1, CYP79D2
L-valine + NADPH + oxygen → N-hydroxy-L-valine + NADP+ + H2O ,
N-hydroxy-L-valine + NADPH + H+ + oxygen → N,N-dihydroxy-L-valine + NADP+ + H2O ,
N,N-dihydroxy-L-valine + H+ → (E)-2-methylpropanal-oxime + CO2 + H2O
Standard Gibbs Free Energy (ΔrG'° in kcal/mol): -198.98792 [Latendresse13]
Enzyme Commission Summary:
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 184.108.40.206 (isoleucine N-monooxygenase), which prefers L-isoleucine.
Andersen00: Andersen MD, Busk PK, Svendsen I, Moller BL (2000). "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(3);1966-75. PMID: 10636899
Forslund04: Forslund K, Morant M, Jorgensen B, Olsen CE, Asamizu E, Sato S, Tabata S, Bak S (2004). "Biosynthesis of the nitrile glucosides rhodiocyanoside A and D and the cyanogenic glucosides lotaustralin and linamarin in Lotus japonicus." Plant Physiol 135(1);71-84. PMID: 15122013
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