Lab of Applied Biocatalysis, College of Light Industry and Food Sciences, South China University of Technology, Guangzhou, Guangdong, China.
State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, Guangdong, China.
PLoS One. 2014 Apr 16;9(4):e94543. doi: 10.1371/journal.pone.0094543. eCollection 2014.
A novel carbonyl reductase (AcCR) catalyzing the asymmetric reduction of ketones to enantiopure alcohols with anti-Prelog stereoselectivity was found in Acetobacter sp. CCTCC M209061 and enriched 27.5-fold with an overall yield of 0.4% by purification. The enzyme showed a homotetrameric structure with an apparent molecular mass of 104 kDa and each subunit of 27 kDa. The gene sequence of AcCR was cloned and sequenced, and a 762 bp gene fragment was obtained. Either NAD(H) or NADP(H) can be used as coenzyme. For the reduction of 4'-chloroacetophenone, the Km value for NADH was around 25-fold greater than that for NADPH (0.66 mM vs 0.026 mM), showing that AcCR preferred NADPH over NADH. However, when NADH was used as cofactor, the response of AcCR activity to increasing concentration of 4'-chloroacetophenone was clearly sigmoidal with a Hill coefficient of 3.1, suggesting that the enzyme might possess four substrate-binding sites cooperating with each other The Vmax value for NADH-linked reduction was higher than that for NADPH-linked reduction (0.21 mM/min vs 0.17 mM/min). For the oxidation of isopropanol, the similar enzymological properties of AcCR were found using NAD+ or NADP+ as cofactor. Furthermore, a broad range of ketones such as aryl ketones, α-ketoesters and aliphatic ketones could be enantioselectively reduced into the corresponding chiral alcohols by this enzyme with high activity.
在醋酸杆菌(Acetobacter sp.)CCTCC M209061 中发现了一种新型的羰基还原酶(AcCR),它能够以反-Prelog 立体选择性催化酮不对称还原为对映纯的醇,总收率为 0.4%,经纯化后酶活富集了 27.5 倍。该酶具有四聚体结构,表观分子量为 104 kDa,每个亚基分子量为 27 kDa。克隆并测序了 AcCR 的基因序列,得到了一个 762 bp 的基因片段。该酶既可以 NAD(H)也可以 NADP(H)作为辅酶。对于 4'-氯苯乙酮的还原,NADH 的 Km 值比 NADPH 大约 25 倍(0.66 mM 比 0.026 mM),表明 AcCR 更偏好 NADPH 而不是 NADH。然而,当 NADH 作为辅酶时,AcCR 活性对 4'-氯苯乙酮浓度增加的响应明显呈 S 型,Hill 系数为 3.1,表明该酶可能具有四个相互协作的底物结合位点。NADH 偶联还原的 Vmax 值高于 NADPH 偶联还原的 Vmax 值(0.21 mM/min 比 0.17 mM/min)。对于异丙醇的氧化,使用 NAD+或 NADP+作为辅酶时,AcCR 具有相似的酶学性质。此外,该酶能够高效地将广泛的酮类物质,如芳酮、α-酮酯和脂肪族酮,选择性还原为相应的手性醇。
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