鸟嘌呤四链体中K+移动路径的预测

结合鸟嘌呤四链体(G4)的结构特点,取G4中的一个K+与一片g-tetrad(g-tetrad-K+)为研究对象,和一个K+与两片g-tetrad(1,2-g-tetrads-K+和2,3-g-tetrads-K+)为研究对象.为g-tetrad-K+,1,2-g-tetrads-K+和2,3-g-tetrads-K+三体系中的K+设计了几种移动路径,来探讨G4中K+与g-tetrad的作用.首先分别应用从头计算MP2/6-31G(d,p)和ABEEMσπ/MM(σπ水平的原子键电负性均衡原理融入到分子力学)方法,对g-tetrad-K+中K+移动过程中体系的结构和能量变化进行了详细研究.结果表明ABEEMσπ/MM方法能够准确地描述g-tetrad-K+体系的结构、结合能等性质.为了更接近实际体系,进而用ABEEMσπ/MM方法预测了更大的体系:一个K+和两片g-tetrad.由于体系较大,MP2方法无法计算其结合能.ABEEMσπ/MM方法对g-tetrad-K+,1,2-g-tetrads-K+和2,3-g-tetrads-K+体系中K+移动而产生的结合能变化表明:如果吸收足够的能量,G4中K+最容易沿α方向移出.

Prediction of the Exchanging Route of K+ in Guanine-Quadruplex

Considering the configuration characteristic, this paper takes K+ and one g-tetrad (g-tetrad-K+) as studied object, together with K+ and two g-tetrads (1,2-g-tetrads-K+ and 2,3-g-tetrads-K+) in gua-nine-quadruplex structure (G4) as studied object. We have designed several moving routes for K+ in g-tetrad-K+, 1,2-g-tetrads-K+ and 2,3-g-tetrads-K+ three systems to explore the interaction between g-tetrad and K+. First, ab initio [MP2/6-31G(d,p)] and ABEEMσπ/MM (Atom Bond Electronegativity Equalization Method at σπ level fused into Molecular Mechanics) methods have been used to investigate the changes of structure and energy, when K+ moves in g-tetrad-K+. The results indicate that ABEEMσπ/MM can accurately describe the properties of the g-tetrad-K+ system structure and energy. To approaching the practical system, ABEEMσπ/MM has been used to explore the bigger system K+ and two g-tetrads, which is too big to calculate the interaction energy using MP2. The changes of the interaction energy from ABEEMσπ/MM, when K+ moves in g-tetrad-K+, 1,2-g-tetrads-K+ and 2,3-g-tetrads-K+ systems indicate that if absorb enough energy, it is easiest for the K+ in G4 moves out of the cavity along the α direction.