近日，德国
据研究人员介绍，光解酶是一种利用光催化DNA修复的酶。
为了捕捉参与该酶催化循环的反应中间体，研究人员进行了一次时间分辨晶体学实验。研究人员发现，光解酶以高度弯曲的几何形状捕获了活性辅助因子黄素腺嘌呤二核苷酸（FAD）的激发态。这种激发态可将电子转移到受损的DNA上，从而诱导修复。研究人员发现，修复反应涉及两个共价键的断裂，这是通过单键中间体发生的。底物转化为产物的过程挤占了活性位点，破坏了与酶的氢键，导致产物逐步释放，3′胸腺嘧啶首先喷出，随后是5′碱基。
附：英文原文
Title: Time-resolved crystallography captures light-driven DNA repair
Author: Nina-Eleni Christou, Virginia Apostolopoulou, Diogo V. M. Melo, Matthias Ruppert, Alisia Fadini, Alessandra Henkel, Janina Sprenger, Dominik Oberthuer, Sebastian Günther, Anastasios Pateras, Aida Rahmani Mashhour, Oleksandr M. Yefanov, Marina Galchenkova, Patrick Y. A. Reinke, Viviane Kremling, T. Emilie S. Scheer, Esther R. Lange, Philipp Middendorf, Robin Schubert, Elke De Zitter, Koya Lumbao-Conradson, Jonathan Herrmann, Simin Rahighi, Ajda Kunavar, Emma V. Beale, John H. Beale, Claudio Cirelli, Philip J. M. Johnson, Florian Dworkowski, Dmitry Ozerov, Quentin Bertrand, Maximilian Wranik, Camila Bacellar, Saa Bajt, Soichi Wakatsuki, Jonas A. Sellberg, Nils Huse, Duan Turk, Henry N. Chapman, Thomas J. Lane
Issue&Volume: 2023-12-01
Abstract: Photolyase is an enzyme that uses light to catalyze DNA repair. To capture the reaction intermediates involved in the enzyme’s catalytic cycle, we conducted a time-resolved crystallography experiment. We found that photolyase traps the excited state of the active cofactor, flavin adenine dinucleotide (FAD), in a highly bent geometry. This excited state performs electron transfer to damaged DNA, inducing repair. We show that the repair reaction, which involves the lysis of two covalent bonds, occurs through a single-bond intermediate. The transformation of the substrate into product crowds the active site and disrupts hydrogen bonds with the enzyme, resulting in stepwise product release, with the 3′ thymine ejected first, followed by the 5′ base.
DOI: adj4270
Source: https://www.science.org/doi/10.1126/science.adj4270