Bhattacharya Santanu, Chaudhuri Padmaparna
Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India.
Chem Asian J. 2007 May 4;2(5):648-55. doi: 10.1002/asia.200700014.
Studies of double-stranded-DNA binding have been performed with three isomeric bis(2-(n-pyridyl)-1H-benzimidazole)s (n=2, 3, 4). Like the well-known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+). Ligand-DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2-pyridyl derivative to DNA is dramatically reduced in the presence of Co(2+), Ni(2+), and Cu(2+) ions and is abolished completely at a ligand/metal-cation ratio of 1:1. Control experiments done with the isomeric 3- and 4-pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition-metal ions. The ability of 2-(2-pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.
已对三种同分异构体双（2-（正吡啶基）-1H-苯并咪唑）（n = 2、3、4）进行了双链DNA结合研究。与著名的双苯并咪唑化合物Hoechst 33258一样，这三种异构体与双链DNA的小沟结合。在二价金属离子Mg(2+)、Co(2+)、Ni(2+)、Cu(2+)和Zn(2+)存在的情况下，研究了这三种异构体与DNA的结合。用荧光光谱和圆二色光谱探测配体与DNA的相互作用。这些研究表明，在Co(2+)、Ni(2+)和Cu(2+)离子存在的情况下，2-吡啶基衍生物与DNA的结合显著减少，并且在配体/金属阳离子比例为1:1时完全消除。用同分异构体3-吡啶基和4-吡啶基衍生物进行的对照实验表明，它们与DNA的结合不受上述过渡金属离子的影响。2-（2-吡啶基）苯并咪唑螯合金属离子的能力以及与离子螯合相关的配体构象变化可能导致了邻位异构体这种不寻常的结合结果。添加乙二胺四乙酸（EDTA）可完全逆转这些影响。
