Does the A.T or G.C base-pair possess enhanced stability? Quantifying the effects of CH...O interactions and secondary interactions on base-pair stability using a phenomenological analysis and ab initio calculations.
Does the A.T or G.C base-pair possess enhanced stability? Quantifying the effects of CH...O interactions and secondary interactions on base-pair stability using a phenomenological analysis and ab initio calculations.
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DOI：
10.1021/ja066341f
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发表时间：
2007-01
影响因子：
15
通讯作者：
J. Quinn;S. Zimmerman;Janet E. Del Bene;I. Shavitt
中科院分区：
文献类型：
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作者：
J. Quinn;S. Zimmerman;Janet E. Del Bene;I. Shavitt
开发了整体复合物稳定性（-DeltaG 度）和各种可能的组分相互作用之间基于经验的关系，以探讨 A.T/U 和 G.C 碱基对是否相对于类似的氢键复合物表现出增强的稳定性。这种现象学方法表明大约。由于包含 CH...O 接触的基团相互作用，A.T 具有 2-2.5 kcal mol-1 的额外稳定性。配对几何结构和 CH...O 相互作用在 A.T 碱基对中的作用也使用 MP2/6-31+G(d,p) 计算和双突变体循环进行了探讨。从头开始的研究表明，在 A.T 中，Hoogsteen 几何优于 Watson-Crick 几何。 1 kcal mol-1。可能有助于选择 Hoogsteen 几何结构的因素包括较短的 CH...O 接触、有利的偶极子排列以及二次排斥位点之间的较大距离。 CH...O 相互作用也在腺嘌呤与烯酮和异氰酸的模型配合物中进行了研究。从头计算支持现象学方法的结果，即 A.T 碱基对相对于仅具有 N-H...N 和 N-H...O 氢键的氢键复合物确实具有增强的稳定性。
An empirically based relationship between overall complex stability (-DeltaG degrees ) and various possible component interactions is developed to probe the question of whether the A.T/U and G.C base-pairs exhibit enhanced stability relative to similarly hydrogen-bonded complexes. This phenomenological approach suggests ca. 2-2.5 kcal mol-1 in additional stability for A.T owing to a group interaction containing a CH...O contact. Pairing geometry and the role of the CH...O interaction in the A.T base-pair were also probed using MP2/6-31+G(d,p) calculations and a double mutant cycle. The ab initio studies indicated that Hoogsteen geometry is preferred over Watson-Crick geometry in A.T by ca. 1 kcal mol-1. Factors that might contribute to the preference for Hoogsteen geometry are a shorter CH...O contact, a favorable alignment of dipoles, and greater distances between secondary repulsive sites. The CH...O interaction was also investigated in model complexes of adenine with ketene and isocyanic acid. The ab initio calculations support the result of the phenomenological approach that the A.T base-pair does have enhanced stability relative to hydrogen-bonded complexes with just N-H...N and N-H...O hydrogen bonds.