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报告题目：ENGINEERING IODOTYROSINE DEIODINASE FOR REDUCTIVE DEHALOGENATION OF HALOPHENOLS
报告时间：2026-11-10 15:30
报告人： Professor Steven E. Rokita
Johns Hopkins University
报告地点：卢嘉锡楼202报告厅
转播地点：翔安校区能源材料大楼3号会议室2；漳州校区生化主楼307教室
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.
报告人简介：
Steven Rokita received a B.S. (Chemistry) from the University of California at Berkeley and his Ph.D. in Biological Chemistry from MIT under the direction of Christopher Walsh. He joined the laboratory of E. T. Kaiser (Rockefeller University) as a NIH Postdoctoral Fellow in 1983 and then began his independent career in 1985 as a faculty member of the Chemistry Department at what was then called SUNY at Stony Brook. In 1995, he moved as an associate professor to the Department of Chemistry and Biochemistry at the University of Maryland, College Park and most recently (2012) moved as a professor of Chemistry to Johns Hopkins University where he is also director of the Chemistry-Biology Interface Graduate Training Program.
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