Origin of Na+/K+ selectivity of the guanine tetraplexes in water:: The theoretical rationale
Origin of Na+/K+ selectivity of the guanine tetraplexes in water:: The theoretical rationale
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DOI：
10.1021/jp012739g
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发表时间：
2002-01-24
影响因子：
2.9
通讯作者：
Leszczynski, J
中科院分区：
文献类型：
--
作者：
Gu, JD;Leszczynski, J
在HF/6- 311 G（d，p）//HF 6 - 31 G（d，p）水平上对金属离子（Na ~+和K ~+）G-四联体配合物的“三明治”模型进行了理论研究.在G4-M-G4（内部）模型中，阳离子与鸟嘌呤的O 6原子之间的距离预测为钠为2.826埃，钾为2.951埃，在G4-M-G4（内部）模型中，钠为2.791埃，钾为2.927埃。这些结果与相应晶体结构中2.75 +/-0.02埃的Na+-O 6距离一致。四联体中的阳离子和G四联体之间的结合能对于Na+大于对于K+。这表明在阳离子-四元复合物体系中静电相互作用占主导地位.经水化能校正后，鸟嘌呤四联体中一价阳离子的稳定性顺序为K+ > Na+。这一发现首次提供了直接的理论证据，支持Hud等人的假设，即G四链体中K+相对于Na+的优先配位实际上是由相对水合能决定的。
Theoretical study of the "sandwich" models of the metal ion (Na+ and K+) G-tetrad complexes has been performed at the HF/6-311G(d,p)//HF6-31G(d,p) level. The distances between cations and the O6 atoms of,guanines have been predicted to be 2.826 Angstrom for sodium and 2.951 Angstrom for potassium in the G4-M-G4(inter) model and 2.791 Angstrom for sodium and 2.927 Angstrom for potassium in the G4-M-G4(intra) model. These results are consistent with the Na+-O6 distance of 2.75 +/- 0.02 Angstrom in the corresponding crystal structures. The binding energy between the cations and the G tetrad in the tetraplexes is greater for Na+ than for K+. This suggests the domination of the electrostatic interaction in the cation- tetraplexe s systems. After the hydration energy correction, the stability sequence of monovalence cations in the guanine tetraplexes is found to be K+ > Na+. This finding gives the first direct theoretical evidence to support the hypothesis of Hud et al. that the preferred coordination of K+ over Na+ in G tetraplexes is actually dominated by relative energies of hydration.