Röttger Katharina, Marroux Hugo J B, Chemin Arsène F M, Elsdon Emma, Oliver Thomas A A, Street Steven T G, Henderson Alexander S, Galan M Carmen, Orr-Ewing Andrew J, Roberts Gareth M
School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, U.K.
J Phys Chem B. 2017 May 4;121(17):4448-4455. doi: 10.1021/acs.jpcb.7b02679. Epub 2017 Apr 25.
Transient electronic and vibrational absorption spectroscopies have been used to investigate whether UV-induced electron-driven proton transfer (EDPT) mechanisms are active in a chemically modified adenine-thymine (A·T) DNA base pair. To enhance the fraction of biologically relevant Watson-Crick (WC) hydrogen-bonding motifs and eliminate undesired Hoogsteen structures, a chemically modified derivative of A was synthesized, 8-(tert-butyl)-9-ethyladenine (8tBA). Equimolar solutions of 8tBA and silyl-protected T nucleosides in chloroform yield a mixture of WC pairs, reverse WC pairs, and residual monomers. Unlike previous transient absorption studies of WC guanine-cytosine (G·C) pairs, no clear spectroscopic or kinetic evidence was identified for the participation of EDPT in the excited-state relaxation dynamics of 8tBA·T pairs, although ultrafast (sub-100 fs) EDPT cannot be discounted. Monomer-like dynamics are proposed to dominate in 8tBA·T.
瞬态电子吸收光谱和振动吸收光谱已被用于研究紫外线诱导的电子驱动质子转移（EDPT）机制在化学修饰的腺嘌呤 - 胸腺嘧啶（A·T）DNA碱基对中是否起作用。为了提高生物学相关的沃森 - 克里克（WC）氢键基序的比例并消除不需要的 hoogsteen 结构，合成了一种化学修饰的A衍生物，8 - （叔丁基） - 9 - 乙基腺嘌呤（8tBA）。8tBA与氯仿中的硅烷基保护的T核苷的等摩尔溶液产生WC对、反向WC对和残余单体的混合物。与之前对WC鸟嘌呤 - 胞嘧啶（G·C）对的瞬态吸收研究不同，没有发现明确的光谱或动力学证据表明EDPT参与了8tBA·T对的激发态弛豫动力学，尽管超快（亚100飞秒）EDPT不能被排除。有人提出单体样动力学在8tBA·T中占主导地位。
