Ketol-acid reductoisomerase

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ketol-acid reductoisomerase
Identifiers
EC number 1.1.1.86
CAS number 9075-02-9
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

In enzymology, a ketol-acid reductoisomerase (EC 1.1.1.86) is an enzyme that catalyzes the chemical reaction

(R)-2,3-dihydroxy-3-methylbutanoate + NADP+ \rightleftharpoons (S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+

Thus, the two substrates of this enzyme are (R)-2,3-dihydroxy-3-methylbutanoate and NADP+, whereas its 3 products are (S)-2-hydroxy-2-methyl-3-oxobutanoate, NADPH, and H+.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing). Other names in common use include dihydroxyisovalerate dehydrogenase (isomerizing), acetohydroxy acid isomeroreductase, ketol acid reductoisomerase, alpha-keto-beta-hydroxylacyl reductoisomerase, 2-hydroxy-3-keto acid reductoisomerase, acetohydroxy acid reductoisomerase, acetolactate reductoisomerase, dihydroxyisovalerate (isomerizing) dehydrogenase, isomeroreductase, and reductoisomerase. This enzyme participates in valine, leucine and isoleucine biosynthesis and pantothenate and coa biosynthesis.

Structural studies[edit]

As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1NP3, 1QMG, 1YRL, and 1YVE.

References[edit]

  • Arfin SM, Umbarger HE (1969). "Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium". J. Biol. Chem. 244 (5): 1118–27. PMID 4388025. 
  • Hill RK, Sawada S and Arfin SM (1979). "Stereochemistry of valine and isoleucine biosynthesis. IV Synthesis, configuration, and enzymatic specificity of alpha-acetolactate and alpha-aceto-alpha-hydroxybutyrate". Bioorg. Chem. 8 (2): 175–189. doi:10.1016/0045-2068(79)90003-8. 
  • Kiritani K, Narise S and Wagner RP (1966). "The reductoisomerase of Neurospora crassa". J. Biol. Chem. 241: 2047–2051. 
  • Satyanarayana T, Radhakrishnan AN (1965). "Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus". Biochim. Biophys. Acta 110 (2): 380–8. doi:10.1016/s0926-6593(65)80045-5. PMID 5866387.