CEA, IBITECS, Laboratoire de Photocatalyse et Biohydrogène, 91191 Gif-sur-Yvette, France.
Curr Opin Struct Biol. 2010 Dec;20(6):693-701. doi: 10.1016/j.sbi.2010.07.003. Epub 2010 Aug 10.
DNA photolyase uses visible light and a fully reduced flavin cofactor FADH(-) to repair major UV-induced lesions in DNA, the cyclobutane pyrimidine dimers (CPDs). Electron transfer from photoexcited FADH(-) to CPD, splitting of the two intradimer bonds, and back electron transfer to the transiently formed flavin radical FADH° occur in overall 1ns. Whereas the kinetics of FADH° was resolved, the DNA-based intermediates escaped unambiguous detection yet. Another light reaction, named photoactivation, reduces catalytically inactive FADH° to FADH(-) without implication of DNA. It involves electron hopping along a chain of three tryptophan residues in 30ps, as elucidated in detail by transient absorption spectroscopy. The same triple tryptophan chain is found in cryptochrome blue-light photoreceptors and may be involved in their primary photoreaction.
DNA 光解酶利用可见光和完全还原的黄素辅因子 FADH(-) 修复 DNA 中的主要紫外线诱导损伤，即环丁烷嘧啶二聚体 (CPD)。光激发的 FADH(-) 向 CPD 的电子转移、两个二聚体键的分裂以及向瞬态形成的黄素自由基 FADH°的反向电子转移在总体上发生在 1ns 内。虽然已经解析了 FADH°的动力学，但基于 DNA 的中间体仍未被明确检测到。另一种光反应，称为光激活，在不涉及 DNA 的情况下将无催化活性的 FADH°还原为 FADH(-)。如瞬态吸收光谱所详细阐明的，它涉及沿着三个色氨酸残基链的电子跳跃，该三重色氨酸链在 cryptochrome 蓝光光受体中被发现，并且可能参与其主要光反应。
