Vibrational circular dichroism and IR absorption of DNA complexes with Cu2+ ions
Vibrational circular dichroism and IR absorption of DNA complexes with Cu2+ ions
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DOI：
10.1002/bip.10439
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发表时间：
2003-01-01
期刊：
影响因子：
2.9
通讯作者：
Wieser, H
中科院分区：
文献类型：
--
作者：
Andrushchenko, V;van de Sande, JH;Wieser, H
用振动圆二色光谱（VCD）和同步红外吸收光谱（IR）研究了室温下，Cu ~（2+）浓度为0 ~ 0.4M（Cu ~（2+）/磷酸根摩尔比[Cu]/[P]为0 ~ 0.7）时，天然小牛胸腺DNA与Cu ~（2+）的相互作用。在一些重要的情况下，VCD提供了更详细的见解比以前的IR调查，而在其他几个导致相同的解释。Cu 2+离子在低金属浓度下与磷酸根基团结合。在增加离子浓度时，形成螯合物，其中Cu 2+结合到鸟嘌呤（G）的N-7和磷酸基团。大多数鸟嘌呤-胞嘧啶（GC）碱基对的显著畸变仅可通过VCD检测到，在[Cu]/[P]比为0.5时发生，对腺嘌呤-胸腺嘧啶（AT）碱基对的影响很小，这有利于“三明治”复合物，其中Cu 2+离子插入GpG序列中两个相邻鸟嘌呤之间。当金属浓度增加到0.7 [Cu]/[P]时，AT碱基对变得显著扭曲。许多GC碱基对可能参与夹心复合物，即使在0.7 [Cu]/[P]下也保持堆叠和配对，防止完全链分离。在[Cu]/[P]比为0.4或更高时，DNA二级结构与标准的B型几何结构相比发生了相当大的变化。进一步过渡到一些中间构象，这是不一致的A-或Z-形式或完全变性状态的建议与其他作品。在一般情况下，VCD被证明是DNA-金属离子络合物的三维结构的可靠指标，其揭示了不能单独从IR吸收光谱推断出的结构细节。(C)2003 Wiley Periodicals，Inc.
Vibrational circular dichroism (VCD) spectroscopy and simultaneous IR absorption measurements are applied to study the interaction of natural calf thymus DNA with Cu2+ ions at room temperature in a Cu2+ concentration range of 0-0.4M (a Cu2+/phosphate molar ratio [Cu]/[P] of 0-0.7). In some important instances, VCD provides more detailed insights than previous IR investigations whereas in several others it leads to the same interpretations. The Cu2+ ions bind to phosphate groups at a low metal concentration. Upon increasing the ion concentration, chelates are formed in which Cu2+ binds to the N-7 of guanine (G) and a phosphate group. Detectable only by VCD, significant distortion of most guanine-cytosine (GC) base pairs occurs at a [Cu]/[P] ratio of 0.5 with only a minor affect on adenine-thymine (AT) base pairs, which favors a "sandwich" complex in which a Cu2+ ion is inserted between two adjacent guanines in a GpG sequence. The AT base pairs become significantly distorted when the metal concentration is increased to 0.7 [Cu]/[P]. A number of GC base pairs, which are possibly involved in sandwich complexes, remain stacked and paired even at 0.7 [Cu]/[P], preventing complete strand separation. The DNA secondary structure changes considerably from the standard B-form geometry at a [Cu]/[P] ratio of 0.4 and higher. A further transition to some intermediate conformation that is inconsistent with either the A- or Z-form or a completely denatured state is suggested in agreement with other works. In general, VCD proves to be a reliable indicator of the 3-dimensional structure of the DNA-metal ion complexes, which reveals structural details that cannot be deduced from the IR absorption spectra alone. (C) 2003 Wiley Periodicals, Inc.