Probing the Nature of Three-Centered Hydrogen Bonds in Minor-Groove Ligand−DNA Interactions: The Contribution of Fluorine Hydrogen Bonds to Complex Stability
作者:Zhenhua Sun、Larry W. McLaughlin
DOI:10.1021/ja073981p
日期:2007.10.1
Double-stranded DNA sequences have been prepared in which single atoms (the O2-carbonyls of selected thymines) have been replaced by fluorine or methyl. To maintain normal Watson-Crick hydrogen bonding with the complementary purines, these analogue derivatives have been prepared as C-nucleosides. The O2-carbonyls of interest for this study are those involved in a bifurcated (or three-centered) hydrogen bond with
已制备出双链 DNA 序列,其中单个原子(所选胸腺嘧啶的 O2-羰基)已被氟或甲基取代。为了维持与互补嘌呤的正常 Watson-Crick 氢键,这些类似物衍生物已制备为 C-核苷。本研究感兴趣的 O2-羰基是那些与小沟结合配体 4',6-二脒基-2-苯基吲哚 (DAPI) 形成分叉(或三中心)氢键的化合物。双链体的 TM 研究表明,当氟或甲基取代小沟 O2-羰基中的一个或两个时,DNA 双链体不稳定,这可以部分解释为小沟水合的变化。在 DAPI 的存在下,由于 DAPI 结合在小沟中,大多数双链体表现出增加的 TM。螺旋过度稳定的程度与小沟中一个或两个甲基的存在呈负相关,这表明在非羰基官能团的存在下配体结合减弱。单氟的存在似乎促进螺旋稳定,当两种氟都存在时,会发生类似天然的稳定。KD 值量化了 DAPI 与原生和模拟序列之间的结合效应。带有一个或两个甲基的序列与 DAPI 的结合非常差,