报告题目：Engineering Iodotyrosine Deiodinase for Reductive Dehalogenation of Halophenols

报 告 人：Prof. Steven E. Rokita

报告时间：2026年11月6日（周五）10：00

报告地点：化91社区 化中C512

报告人简介： Steven E. Rokita教授，1979年本科毕业于加州大学伯克利分校化学91社区 ，1983年博士毕业于麻省理工91社区 化学系。Rokita教授先后在University at Stony Brook和University of Maryland担任助理教授、副教授和教授等职位；2012年，加入Johns Hopkins University（约翰霍普金斯大学），成为化学系和生物系的联合教授，并担任化学与生物交叉的研究生培训项目主任。2011年，当选为美国科学促进会院士。Rokita教授在生物有机和生物无机化学，核酸化学和酶学等领域具有广泛的研究兴趣。

报告摘要：The flavoprotein iodotyrosine deiodinase promotes reductive dehalogenation of chloro-, bromo-, and iodotyrosine with reasonable efficiency and offers an appealing system for dehalogenating a variety of halogen-containing phenols that persist in the environment. This enzyme relies on stabilization of a FMN semiquinone intermediate and an associated series of single-electron transfer steps for turnover. While the active site of the protein facilitates this process, catalysis is primarily controlled by substrate. As expected from much precedence, a side chain hydroxy group is available for H-bonding with the N5 position of FMN to promote semiquinone formation, but its contribution to catalysis is surprisingly modest. Closure of an active site lid is even less important for dehalogenation. In contrast, the reduction potential of the deiodinase is lowered by approximately 100 mV and its chemistry switches from two-electron to one-electron processes after fluorotyrosine, an inert substrate analog, binds to the active site. Even more significant is the substrate zwitterion for promoting catalysis and stabilizing the necessary FMN semiquinone. Of course, this presents a significant barrier for substates such as the desired halophenols that lack a zwitterion. However, directed evolution of key active site residues significantly enhances dehalogenation of iodo-, bromo- and chlorophenols.