School of Food Engineering, Anhui Science and Technology University, Chuzhou 233100, China.
Department of Cardiology, Affiliated Hospital of Jiangnan University, Wuxi 214122, China.
Molecules. 2023 Apr 30;28(9):3831. doi: 10.3390/molecules28093831.
Theaflavins (TFs) are good for health because of their bioactivities. Enzymatic synthesis of TFs has garnered much attention; however, the source and activity of the enzymes needed limit their wide application. In this study, a microbial polyphenol oxidase from was screened for the synthesis of theaflavin-3,3'-digallate (TFDG). Based on structural and mechanistic analyses of the enzyme, the O-O bond dissociation was identified as the rate-determining step. To address this issue, a transition state (TS) conformation optimization strategy was adopted to stabilize the spatial conformation of the O-O bond dissociation, which improved the catalytic efficiency of tyrosinase. Under the optimum transformation conditions of pH 4.0, temperature 25 °C, (-)-epigallocatechin gallate/epicatechin gallate molar ratio of 2:1, and time of 30 min, Mu (Tyr) produced 960.36 mg/L TFDG with a 44.22% conversion rate, which was 6.35-fold higher than that of the wild type. Thus, the method established has great potential in the synthesis of TFDG and other TFs.
茶黄素（TFs）因其生物活性而有益于健康。由于其所需的酶的来源和活性限制了其广泛应用，因此人们对 TFs 的酶法合成产生了浓厚的兴趣。在这项研究中，从 筛选到一种微生物多酚氧化酶，用于合成茶黄素-3,3′-二没食子酸酯（TFDG）。基于对该酶的结构和机制分析，确定 O-O 键的离解为速率决定步骤。为了解决这个问题，采用了过渡态（TS）构象优化策略来稳定 O-O 键离解的空间构象，从而提高了酪氨酸酶的催化效率。在最适转化条件下（pH4.0、温度 25°C、（-）-表没食子儿茶素没食子酸酯/表儿茶素没食子酸酯摩尔比为 2:1、时间 30min），Mu（Tyr）产生了 960.36mg/L 的 TFDG，转化率为 44.22%，比野生型提高了 6.35 倍。因此，该方法在 TFDG 和其他 TFs 的合成方面具有很大的潜力。
