(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

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

References

• Arfin SM, Umbarger HE "Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium". J. Biol. Chem. 244 1118–27.
• Hill RK, Sawada S and Arfin SM "Stereochemistry of valine and isoleucine biosynthesis. IV Synthesis, configuration, and enzymatic specificity of alpha-acetolactate and alpha-aceto-alpha-hydroxybutyrate". Bioorg. Chem. 8 175–189.
• Kiritani K, Narise S and Wagner RP "The reductoisomerase of Neurospora crassa". J. Biol. Chem. 241 2047–2051.
• Satyanarayana T, Radhakrishnan AN "Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus". Biochim. Biophys. Acta. 110 380–8.

External links

The CAS registry number for this enzyme class is .

Gene Ontology (GO) codes