Fort Towson – Department of Oklahoma

2,3-Dihydroxy-3-methylpentanoic acid is an intermediate in the metabolism of isoleucine.

Metabolism

2,3-Dihydroxy-3-methylpentanoate is synthesized by the action of acetolactate mutase with subsequent reduction from α-aceto-α-hydroxybutyrate through 3-hydroxy-2-keto-3-methylpentanoate:^[1]

α-aceto-α-hydroxybutyrate → 3-hydroxy-2-keto-3-methylpentanoate

3-hydroxy-2-keto-3-methylpentanoate + NAD(P)H → 2,3-dihydroxy-3-methylpentanoate + NAD(P)⁺

It is then processed by the action of dihydroxyacid dehydratase, which results in 2-keto-3-methylvalerate and water:^[1]

2,3-dihydroxy-3-methylpentanoate → 2-keto-3-methylvalerate + H₂O

Transamination of 2-keto-3-methylvalerate yields isoleucine.

^ ^a ^b Voet, Donald; Voet, Judith G. (2011). Biochemistry (4. ed.). Hoboken, NJ: Wiley. pp. 1074–1075. ISBN 978-0-470-91745-9.

lysine→	Saccharopine Allysine α-Aminoadipic acid 2-Oxoadipic acid Glutaryl-CoA Glutaconyl-CoA Crotonyl-CoA β-Hydroxybutyryl-CoA
leucine→	β-Hydroxy β-methylbutyric acid β-Hydroxy β-methylbutyryl-CoA Isovaleryl-CoA α-Ketoisocaproic acid β-Ketoisocaproic acid β-Ketoisocaproyl-CoA β-Leucine β-Methylcrotonyl-CoA β-Methylglutaconyl-CoA β-Hydroxy β-methylglutaryl-CoA
tryptophan→alanine→	N′-Formylkynurenine Kynurenine Anthranilic acid 3-Hydroxykynurenine 3-Hydroxyanthranilic acid 2-Amino-3-carboxymuconic semialdehyde 2-Aminomuconic semialdehyde 2-Aminomuconic acid Glutaryl-CoA

glycine→ serine→	3-Phosphoglyceric acid glycine→creatine: Glycocyamine Phosphocreatine Creatinine

histidine→	Urocanic acid Imidazol-4-one-5-propionic acid Formiminoglutamic acid Glutamate-1-semialdehyde
proline→	1-Pyrroline-5-carboxylic acid
arginine→	Agmatine Ornithine Citrulline Cadaverine Putrescine
other	cysteine+glutamate→glutathione: γ-Glutamylcysteine

valine→	α-Ketoisovaleric acid Isobutyryl-CoA Methacrylyl-CoA 3-Hydroxyisobutyryl-CoA 3-Hydroxyisobutyric acid 2-Methyl-3-oxopropanoic acid
isoleucine→	2,3-Dihydroxy-3-methylpentanoic acid 2-Methylbutyryl-CoA Tiglyl-CoA 2-Methylacetoacetyl-CoA
methionine→	generation of homocysteine: S-Adenosyl methionine S-Adenosyl-L-homocysteine Homocysteine conversion to cysteine: Cystathionine α-Ketobutyric acid + Cysteine
threonine→	α-Ketobutyric acid
propionyl-CoA→	Methylmalonyl-CoA

phenylalanine→tyrosine→	4-Hydroxyphenylpyruvic acid Homogentisic acid 4-Maleylacetoacetic acid

Other

Cysteine metabolism	Cysteine sulfinic acid