| EC |
1.1.1.86 |
| Accepted name: |
ketol-acid reductoisomerase (NADP+) |
| Reaction: |
(2R)-2,3-dihydroxy-3-methylbutanoate + NADP+ = (2S)-2-hydroxy-2-methyl-3-oxobutanoate + NADPH + H+ |
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For diagram of isoleucine and valine biosynthesis, click here |
| Glossary: |
(2S)-2-hydroxy-2-methyl-3-oxobutanoate = (2S)-2-acetolactate |
| Other name(s): |
dihydroxyisovalerate dehydrogenase (isomerizing); acetohydroxy acid isomeroreductase; ketol acid reductoisomerase; α-keto-β-hydroxylacyl reductoisomerase; 2-hydroxy-3-keto acid reductoisomerase; acetohydroxy acid reductoisomerase; acetolactate reductoisomerase; dihydroxyisovalerate (isomerizing) dehydrogenase; isomeroreductase; reductoisomerase; ketol-acid reductoisomerase; (R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing) |
| Systematic name: |
(2R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing) |
| Comments: |
Also catalyses the reduction of 2-ethyl-2-hydroxy-3-oxobutanoate to 2,3-dihydroxy-3-methylpentanoate. The enzyme, found in many bacteria and archaea, is specific for NADPH (cf. EC 1.1.1.382, ketol-acid reductoisomerase (NAD+) and EC 1.1.1.383, ketol-acid reductoisomerase [NAD(P)+]). |
| Links to other databases: |
BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9075-02-9 |
| References: |
| 1. |
Arfin, S.M. and Umbarger, H.E. Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium. J. Biol. Chem. 244 (1969) 1118–1127. [PMID: 4388025] |
| 2. |
Hill, R.K., Sawada, S. and Arfin, S.M. Stereochemistry of valine and isoleucine biosynthesis. IV. Synthesis, configuration, and enzymatic specificity of α-acetolactate and α-aceto-α-hydroxybutyrate. Bioorg. Chem. 8 (1979) 175–189. |
| 3. |
Kiritani, K., Narise, S. and Wagner, R.P. The reductoisomerase of Neurospora crassa. J. Biol. Chem. 241 (1966) 2047–2051. |
| 4. |
Satyanarayana, T. and Radhakrishnan, A.N. Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus. Biochim. Biophys. Acta 110 (1965) 380–388. [PMID: 5866387] |
| 5. |
Brinkmann-Chen, S., Cahn, J.K. and Arnold, F.H. Uncovering rare NADH-preferring ketol-acid reductoisomerases. Metab. Eng. 26C (2014) 17–22. [DOI] [PMID: 25172159] |
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| [EC 1.1.1.86 created 1972, modified 1976, modified 1981 (EC 1.1.1.89 created 1972, incorporated 1976), modified 2015] |
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