Burchkardt G, Zimmer G, Luck G
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。