Ketol-acid reductoisomerase

{{infobox enzyme

| Name = ketol-acid reductoisomerase

| EC_number = 1.1.1.86

| CAS_number = 9075-02-9

| GO_code = 0004455

| image = 4tsk.jpg

| width = 270

| caption = Ketol-acid reductoisomerase tetramer, Alicyclobacillus acidocaldarius

}}

In enzymology, a ketol-acid reductoisomerase ({{EC number|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

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

References

{{cite journal | vauthors = Arfin SM, Umbarger HE | date = 1969 | title = Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium | journal = J. Biol. Chem. | volume = 244 | pages = 1118–27 | pmid = 4388025 | issue = 5 | doi = 10.1016/S0021-9258(18)91816-8 | doi-access = free }}
{{cite journal | vauthors = Hill RK, Sawada S, Arfin SM | date = 1979 | title = Stereochemistry of valine and isoleucine biosynthesis. IV Synthesis, configuration, and enzymatic specificity of alpha-acetolactate and alpha-aceto-alpha-hydroxybutyrate | journal = Bioorg. Chem. | volume = 8 | pages = 175–189 | doi = 10.1016/0045-2068(79)90003-8 | issue = 2 }}
{{cite journal | vauthors = Kiritani K, Narise S, Wagner RP | date = 1966 | title = The reductoisomerase of Neurospora crassa | journal = J. Biol. Chem. | volume = 241 | issue = 9 | pages = 2047–2051 | doi = 10.1016/S0021-9258(18)96664-0 | doi-access = free }}
{{cite journal | vauthors = Satyanarayana T, Radhakrishnan AN | date = 1965 | title = Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus | journal = Biochim. Biophys. Acta | volume = 110 | pages = 380–8 | pmid = 5866387 | issue = 2 | doi=10.1016/s0926-6593(65)80045-5}}

Category:EC 1.1.1

Category:NADPH-dependent enzymes

Category:Enzymes of known structure