Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
Corporate Research Center, Innovation and Business Development Headquarters, Arai Plant, Daicel Corporation, 1-1 Shinko-cho, Myoko-shi, Niigata 944-8550, Japan.
J Biosci Bioeng. 2020 May;129(5):552-557. doi: 10.1016/j.jbiosc.2019.11.014. Epub 2020 Jan 23.
The gut bacterium Gordonibacter urolithinfaciens DSM 27213 metabolizes ellagic acid into three polyphenol compounds, namely, urolithin M5, urolithin M6, and urolithin C, which are collectively called urolithin. The key reactions of this metabolic pathway are the dehydroxylation of the phenolic hydroxy group, i.e., conversion of urolithin M5 to urolithin M6, and successive conversion of urolithin M6 to urolithin C. By testing the effects of various electron-transferring compounds on the dehydroxylation reactions, methylviologen was found to effectively support the dehydroxylation catalyzed by the cell free extracts. The urolithin dehydroxylating enzymes were found in the soluble fraction of the cell free extracts. The urolithin dehydroxylation was found to be coupled with reduction of dicationic methylviologen to a cation radical form catalyzed by enzymes with hydrogen as an electron donor, which was also found with the soluble fraction. Further investigation of the reaction in the presence of natural cofactors with or without methylviologen and hydrogen revealed the involvement of NADPH and FAD in the electron transportation systems of the urolithin dehydroxylation.
肠道细菌戈登氏菌（Gordonibacter urolithinfaciens）DSM 27213 将鞣花酸代谢为三种多酚化合物，即尿石素 M5、尿石素 M6 和尿石素 C，它们统称为尿石素。该代谢途径的关键反应是酚羟基的去羟基化，即尿石素 M5 转化为尿石素 M6，以及尿石素 M6 连续转化为尿石素 C。通过测试各种电子转移化合物对去羟基化反应的影响，发现甲紫精可有效支持无细胞提取物催化的去羟基化。尿石素去羟化酶存在于无细胞提取物的可溶性部分中。发现尿石素去羟化与二价阳离子甲紫精的还原偶联，由酶以氢作为电子供体催化，在可溶性部分也发现了这种情况。在存在或不存在甲紫精和氢的天然辅因子的情况下进一步研究反应，揭示了 NADPH 和 FAD 参与尿石素去羟化的电子传递系统。
