与蛋白质形成复合物的DNA的构象和反应活性。IV. 聚-L-组氨酸与DNA聚合物模型复合物的圆二色性及相互作用的特异性
Conformation and reactivity of DNA in the complex with protein. IV. Circular dichroism of poly-L-histidine model complexes with DNA polymers and specificity of the interaction.
作者信息
Burchkardt G, Zimmer G, Luck G
出版信息
Nucleic Acids Res. 1976 Mar;3(3):561-80. doi: 10.1093/nar/3.3.561.
The CD study of the DNA-poly-L-histidine complex at high degree of protonation revealed that complex formation is already observable at 2 M NaCl. The influence of salt together with 5 M urea suggests that in addition to electrostatic interactions probably hydrogen bonding may favour specific complexes. Affinity of protonated histidines to AT-rich regions is strongly supported by the complexes formed with (dA.dT)-containing polymers. The psi-type structure occurs with poly(dA-dT)-poly(dA-dT) while poly(dA)-poly(dT) is restricted to form a similar psi-state on interaction with highly protonated poly-L-histidine. Differences in the helix winding properties due to variation in the sequence is suggested as a possible factor in the formation of the psi-type complexes. The mechanism of interaction including hydrogen bonding of histidine side-chains with an AT pair at high degree of protonation and with GC-regions at lower degree of protonation in the polypeptide structure is discussed.
对高度质子化的DNA-聚-L-组氨酸复合物进行的圆二色性（CD）研究表明，在2M氯化钠条件下即可观察到复合物的形成。盐与5M尿素的共同影响表明，除静电相互作用外，氢键可能也有利于形成特定的复合物。与含（dA.dT）聚合物形成的复合物有力地支持了质子化组氨酸对富含AT区域的亲和力。聚（dA-dT）-聚（dA-dT）会形成ψ型结构，而聚（dA）-聚（dT）在与高度质子化的聚-L-组氨酸相互作用时则局限于形成类似的ψ态。由于序列变化导致的螺旋缠绕特性差异被认为是形成ψ型复合物的一个可能因素。文中讨论了在多肽结构中，组氨酸侧链在高度质子化时与AT碱基对以及在较低质子化程度时与GC区域形成氢键的相互作用机制。
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