Burckhardt G, Zimmer C, Luck G
Nucleic Acids Res. 1976 Mar;3(3):537-59. doi: 10.1093/nar/3.3.537.
Differences in the interaction of poly-L-histidine with DNA of various base composition have been demonstrated using melting and CD measurements. The two types of complexes formed with DNA at pH values below the pK of 5.9 and in the region of pH 6.5 are very different in their CD spectral properties. The binding effects with highly protonated poly-L-histidine are AT-dependent as reflected by large negative CD spectra indicating the formation of psi-DNA as a condensed state of the double helix. GC-rich DNA may, however, also form psi-DNA structures with poly-L-histidine under certain conditions. At pH 6.5 complex formation with the weakly protonated polypeptide is GC-dependent. From the results it is concluded that protonated poly-L-histidine interacts more specifically at AT base pairs, prabably along the small groove while the weakly protonated poly-L-histidine tends to interact preferentially with GC regions which seems to occur rather in the large groove.
通过熔解和圆二色性(CD)测量,已证明聚-L-组氨酸与不同碱基组成的DNA相互作用存在差异。在pH值低于5.9的pK以及pH 6.5区域与DNA形成的两种复合物,其CD光谱特性有很大不同。高度质子化的聚-L-组氨酸的结合效应依赖于AT,这表现为大的负CD光谱,表明形成了ψ-DNA,即双螺旋的一种凝聚状态。然而,富含GC的DNA在某些条件下也可能与聚-L-组氨酸形成ψ-DNA结构。在pH 6.5时,与弱质子化多肽形成复合物依赖于GC。从结果可以得出结论,质子化的聚-L-组氨酸可能沿着小沟在AT碱基对处更特异性地相互作用,而弱质子化的聚-L-组氨酸倾向于优先与GC区域相互作用,这似乎更多地发生在大沟中。