(R) 2,3-Dihydroxy-3-methylvalerate → 3-Methyl-2-oxovaleric acid + Water
acetolactate synthase / acetohydroxybutanoate synthase
(S)-2-Acetolactate ↔ 3-Hydroxy-3-methyl-2-oxobutanoic acid
3-Methyl-2-oxovaleric acid + L-Glutamic acid → L-Valine + Oxoglutaric acid
(R)-2,3-Dihydroxy-isovalerate + Hydrogen Ion + NADPH → (R) 2,3-Dihydroxy-3-methylvalerate + NADP
branched-chain amino-acid aminotransferase
Hydrogen Ion + 2 Pyruvic acid → (S)-2-Acetolactate + Carbon dioxide
2-Isopropyl-3-oxosuccinate + Hydrogen Ion → Carbon dioxide + Ketoleucine
Secondary Metabolites: Valine and L-Leucine Biosynthesis from Pyruvate
Ketoleucine + L-Glutamic acid → L-Leucine + Oxoglutaric acid
3-Methyl-2-oxovaleric acid + Acetyl-CoA + Water → 2-Isopropylmalic acid + Coenzyme A + Hydrogen Ion
2-Isopropylmalic acid → Isopropylmaleate + Water
Isopropylmaleate + Water → 3-Isopropylmalate
3-Isopropylmalate + NAD → 2-Isopropyl-3-oxosuccinate + Hydrogen Ion + NADH