酮醇酸還原異構酶

酮醇酸還原異構酶（英語：ketol-acid reductoisomerase，EC 1.1.1.86 （頁面存檔備份，存於網際網路檔案館））是一種以NAD⁺或NADP⁺為受體、作用於供體CH-OH基團上的氧化還原酶。這種酶能催化以下酶促反應：

酮醇酸還原異構酶
命名 系統命名 (R)-2,3-dihydroxy-3-methylbutanoate:NADP+ oxidoreductase (isomerizing) 縮寫 KARI 別名 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
識別碼
EC編號	1.1.1.86
CAS號	9075-02-9
數據庫
IntEnz	IntEnz瀏覽
BRENDA	BRENDA入口
ExPASy	NiceZyme瀏覽
KEGG	KEGG入口
MetaCyc	代謝路徑
PRIAM	概述
PDB	RCSB PDB PDBj PDBe PDBsum
基因本體	AmiGO / EGO
搜索 PMC 相關文獻 PubMed 相關文獻

(R)-2,3-二羥基-3-甲基丁酸 + NADP⁺ $\rightleftharpoons$ (S)-2-羥基-2-甲基-3-氧代丁酸 + NADPH + H⁺

酮醇酸還原異構酶還能將2-乙酰-2-羥基丁酸催化轉化為2,3-二羥基-3-甲基戊酸。

參考文獻

• Arfin SM, Umbarger HE. Purification and properties of the acetohydroxy acid isomeroreductase of Salmonella typhimurium. J. Biol. Chem. 1969, 244 (5): 1118–27. PMID 4388025. 

• 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. 1979, 8 (2): 175–189. doi:10.1016/0045-2068(79)90003-8. 

• Kiritani K, Narise S and Wagner RP. The reductoisomerase of Neurospora crassa. J. Biol. Chem. 1966, 241: 2047–2051. 

• Satyanarayana T, Radhakrishnan AN. Biosynthesis of valine and isoleucine in plants. 3. Reductoisomerase of Phaseolus radiatus. Biochim. Biophys. Acta. 1965, 110 (2): 380–8. PMID 5866387.