Douki Thierry
Laboratoire Lésions des Acides Nucléiques, Service de Chimie Inorganique et Biologique UMR-E 3 CEA-UJF, CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, 38054, Grenoble Cedex 9, France.
Photochem Photobiol Sci. 2006 Nov;5(11):1045-51. doi: 10.1039/b604517k. Epub 2006 Aug 16.
Exposure of DNA to far-UV radiation leads to the formation of several types of dimeric lesions, including cyclobutane dimers and (6-4) photoproducts. In order to gain insights into the main parameters driving DNA photochemistry, the effect of ionic strength on the yield of formation of these photoproducts was investigated in UVC-irradiated samples of isolated genomic DNA. The main consequence of lowering the ionic strength was a decrease in the UVC-induced formation of thymine-cytosine and cytosine-cytosine photoproducts. The reactivity of thymine-thymine and cytosine-thymine doublets was hardly affected. Evidence was obtained against a major role played by duplex denaturation in these observations. A more likely explanation is a change in the DNA structure as the result of a larger extent of protonation at low counter-ions concentration.
DNA暴露于远紫外线辐射会导致形成几种类型的二聚体损伤，包括环丁烷二聚体和（6-4）光产物。为了深入了解驱动DNA光化学的主要参数，在分离的基因组DNA的UVC辐照样品中研究了离子强度对这些光产物形成产率的影响。降低离子强度的主要结果是UVC诱导的胸腺嘧啶-胞嘧啶和胞嘧啶-胞嘧啶光产物的形成减少。胸腺嘧啶-胸腺嘧啶和胞嘧啶-胸腺嘧啶双链体的反应性几乎没有受到影响。有证据表明双链变性在这些观察结果中不起主要作用。一个更可能的解释是，在低抗衡离子浓度下，由于质子化程度更大，DNA结构发生了变化。
