Ene reductases (ERs) are attractive biocatalysts in terms of their high enantioselectivity and expanded substrate scope. Recent works have proved that synthetic nicotinamide coenzyme biomimetics (NCBs) can be used as easily accessible alternatives to natural cofactors in ER-catalyzed reactions. However, the structure-reactivity relationships between NCBs and ERs and influence factors are still poorly understood. In this study, a series of C-5 methyl modified NCBs were synthesized and tested in the PETNR-catalyzed asymmetric reductions. The physicochemical properties of these NCBs including electrochemical properties, stability, and kinetic behavior were studied in detail. The results showed that hydrophobic interaction caused by the introduced methyl group contributed to the stabilization of binding conformation in enzyme active site, resulting in comparable catalytic activity with that of NADPH. Molecular dynamics and steered molecular dynamics simulations were further performed to explain the binding mechanism between PETNR and NCBs, which revealed that stable catalytic conformation, appropriate donor-acceptor distance and angle, as well as free dissociation energy are important factors affecting the activity of NCBs.

中文翻译：

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研究烟酰胺辅酶仿生学与季戊四醇四硝酸酯还原酶之间的结构-反应关系

就其高对映选择性和扩大的底物范围而言，烯还原酶 (ER) 是有吸引力的生物催化剂。最近的工作证明，合成的烟酰胺辅酶仿生学 (NCB) 可用作 ER 催化反应中天然辅因子的易于获得的替代品。然而，NCBs和ERs之间的结构-反应关系以及影响因素仍然知之甚少。在这项研究中，合成了一系列 C-5 甲基修饰的 NCB，并在 PETNR 催化的不对称还原中进行了测试。详细研究了这些 NCB 的理化性质，包括电化学性质、稳定性和动力学行为。结果表明，引入甲基引起的疏水相互作用有助于酶活性位点结合构象的稳定，导致与 NADPH 相当的催化活性。进一步进行分子动力学和分子动力学模拟以解释PETNR与NCBs之间的结合机制，表明稳定的催化构象、合适的供体-受体距离和角度以及自由解离能是影响NCBs活性的重要因素。