Maize (Zea mays) caffeate 3-O-methyltransferase (ZmaysCOMT, EC 2.1.1.68), a key enzyme of the phenylpropanoid pathway, catalyzes the O-methylation of caffeic acid to ferulic acid, a precursor of lignin polymer and a crucial component of the cell wall structure. Plant cell wall recalcitrance is due to lignin, and the discovery of specific inhibitors of ZmaysCOMT could be useful to increase the digestibility of the lignocellulose biomass and improve the production of cellulosic biofuels. In this work, we have modeled the three-dimensional structure of ZmaysCOMT and prospected promising inhibitors by using virtual screening techniques. A set of 1668 putative candidates was screened from a virtual library and docked in the active site of the enzyme, and nitecapone was selected as one of the most promising enzyme inhibitors. Details of the mode of inhibition were assessed by in silico simulation and in vitro assays of nitecapone on the enzyme. In comparison with the nitecapone-free control, kinetics parameters showed different values of Vmax and KM, suggesting a kinetic profile such as mixed inhibition of the ZmaysCOMT. In brief, we suggest that the nitecapone-induced inhibition of ZmaysCOMT may serve as a non-transgenic strategy to explore the biosynthesis of ferulic acid and lignin, their relationships with the recalcitrance of lignocellulosic biomass, and, possibly, to improve bioethanol production.

中文翻译：

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Nitecapone 抑制玉米咖啡酸 3-O-甲基转移酶作为减少木质纤维素生物质抵抗的可能方法

玉米 (Zea mays) 咖啡酸 3-O-甲基转移酶 (ZmaysCOMT, EC 2.1.1.68) 是苯丙烷途径的关键酶，可催化咖啡酸 O-甲基化为阿魏酸，这是木质素聚合物的前体和细胞壁结构。植物细胞壁的顽固性是由木质素引起的，ZmaysCOMT 的特异性抑制剂的发现可能有助于提高木质纤维素生物质的消化率并改善纤维素生物燃料的生产。在这项工作中，我们通过使用虚拟筛选技术对 ZmaysCOMT 的三维结构进行了建模，并展望了有前景的抑制剂。从虚拟文库中筛选出一组1668个推定候选物，并停靠在酶的活性位点，尼特卡朋被选为最有前途的酶抑制剂之一。抑制模式的详细信息通过计算机模拟和尼特卡朋对酶的体外测定进行评估。与不含尼特卡朋的对照相比，动力学参数显示出不同的 Vmax 和 KM 值，这表明动力学特征如对 ZmaysCOMT 的混合抑制。简而言之，我们建议尼替卡朋诱导的 ZmaysCOMT 抑制可以作为一种非转基因策略来探索阿魏酸和木质素的生物合成，它们与木质纤维素生物质的顽固性的关系，并可能提高生物乙醇的生产。表明动力学特征，例如对 ZmaysCOMT 的混合抑制。简而言之，我们建议尼替卡朋诱导的 ZmaysCOMT 抑制可以作为一种非转基因策略来探索阿魏酸和木质素的生物合成，它们与木质纤维素生物质的顽固性的关系，并可能改善生物乙醇的生产。表明动力学特征，例如对 ZmaysCOMT 的混合抑制。简而言之，我们建议尼替卡朋诱导的 ZmaysCOMT 抑制可以作为一种非转基因策略来探索阿魏酸和木质素的生物合成，它们与木质纤维素生物质的顽固性的关系，并可能提高生物乙醇的生产。