Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb²⁺.
Kinetics and mechanism of G-quadruplex formation and conformational switch in a G-quadruplex of PS2.M induced by Pb²⁺.
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Pb2诱导的PS2.M G-四链体形成和构象转换的动力学和机制
DOI：
10.1093/nar/gkr1310
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发表时间：
2012-05
影响因子：
14.9
通讯作者：
Liang H
中科院分区：
文献类型：
--
作者：
Liu W;Zhu H;Zheng B;Cheng S;Fu Y;Li W;Lau TC;Liang H
具有鸟嘌呤重复序列的DNA序列在特定金属离子的存在下可以形成采用G-四链体结构的G-四联体。利用圆二色性（CD）和紫外-可见（UV-Vis）光谱，我们确定了具有寡核苷酸序列d（GTG 3 TAG 3CG 3 TTG 2）的PS2.M的G-四链体的光谱特征和整体构象。紫外-熔解曲线表明，Pb 2+诱导的G-四链体是单分子形成的，最高熔解温度（Tm）为72°C。对紫外滴定结果的分析表明，Pb ~（2+）离子与PS ~（2.M）的结合化学计量比为2，表明Pb ~（2+）离子在相邻的G-四联体之间配位。离子与富G DNA的结合是一个复杂的多途径过程，其强烈地受阳离子类型的影响。动力学研究表明，Pb 2+诱导的PS2.M到G-四链体的折叠可能是通过一个三步途径，涉及两个中间体。在Na+或K+诱导的G-四链体中加入Pb（NO3）2后发生了结构转变，这可能是由于Pb 2+离子取代了Na+或K+，并产生了更致密的Pb 2 +-PS2.M结构。比较弛豫时间发现Na+→ Pb ~（2+）交换过程比K+→ Pb ~（2+）交换过程更容易，并提出了这两个过程的机理。
DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV–Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of PS2.M with an oligonucleotide sequence, d(GTG3TAG3CG3TTG2). UV-melting curves demonstrate that the Pb2+-induced G-quadruplex formed unimolecularly and the highest melting temperature (Tm) is 72°C. The analysis of the UV titration results reveals that the binding stoichiometry of Pb2+ ions to PS2.M is two, suggesting that the Pb2+ ions coordinate between adjacent G-quartets. Binding of ions to G-rich DNA is a complex multiple-pathway process, which is strongly affected by the type of the cations. Kinetic studies suggest that the Pb2+-induced folding of PS2.M to G-quadruplex probably proceeds through a three-step pathway involving two intermediates. Structural transition occurs after adding Pb(NO3)2 to the Na+- or K+-induced G-quadruplexes, which may be attributed to the replacement of Na+ or K+ by Pb2+ ions and the generation of a more compact Pb2+–PS2.M structure. Comparison of the relaxation times shows that the Na+→Pb2+ exchange is more facile than the K+→Pb2+ exchange process, and the mechanisms for these processes are proposed.
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影响因子：
5.6
作者：
Kelly, JA;Feigon, J;Yeates, TO
通讯作者：
Yeates, TO
影响因子：
14.9
作者：
Lane AN;Chaires JB;Gray RD;Trent JO
通讯作者：
Trent JO
DOI：
10.1073/pnas.241374798
发表时间：
2001-11-20
影响因子：
11.1
作者：
Deng, JP;Xiong, Y;Sundaralingam, M
通讯作者：
Sundaralingam, M
影响因子：
2.9
作者：
Majhi, Pinaki R.;Qi, Jianying;Shafer, Richard H.
通讯作者：
Shafer, Richard H.
影响因子：
2.9
作者：
Hud, NV;Smith, FW;Feigon, J
通讯作者：
Feigon, J