高等学校化学学报

高等学校化学学报

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最短α-螺旋的理论研究

蒋帆1,2, 吴云东1,2   

  1. 1. 北京大学深圳研究生院, 化学基因组学实验室, 深圳 518055; 2. 香港科技大学化学系, 香港
  • 收稿日期:2008-11-06 修回日期:1900-01-01 出版日期:2008-12-10 发布日期:2008-12-10

Theoretical Studies on Shortest α-Helix

JIANG Fan1,2, WU Yun-Dong1,2*   

  1. 1. Laboratory of Chemical Genomics, Shenzhen Graduate School of Peking University, Shenzhen 518055, China;2. Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong SAR, China
  • Received:2008-11-06 Revised:1900-01-01 Online:2008-12-10 Published:2008-12-10

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摘要： 在B3LYP/6-31+G**水平下的溶剂中优化得到4个残基长和5个残基长的α-螺旋. 计算得到的骨架构象与蛋白质晶体结构的统计结果符合得很好. 类似于一般的较长α-螺旋, 观察到了C-端的散开. 对很短的聚丙氨酸肽链, 从焓上看310-螺旋明显比α-螺旋稳定, 然而熵效应不利于310-螺旋结构. 螺旋N2(N-端第二个残基)位上天冬氨酸侧链的加盖(Capping)效应明显使α-螺旋相对310-螺旋更加稳定. 因而, 在同样长度下α-螺旋比310-螺旋多的统计结果能够被理解. 另外, 最短的α-螺旋的C-端倾向于以β-转角结构结束.

关键词: α-螺旋, 310-螺旋, 密度泛函理论(DFT)计算, 氢键加盖

Abstract: We present the fully optimized structures of 4-residue and 5-residue α-helices at the B3LYP/6-31+G** level in solvent. The calculated backbone conformations are in good agreement with the statistical results from protein crystal structures. Similar to long regular α-helices, the fraying of the C-teriminal is observed. For short polyalanine peptide, 310-helix is significantly more stable than α-helix in enthalpy. However, the 310-helix is destabilized by entropy effect. In addition, it has been found that the capping effect by an aspartic acid at N2(second residue from the N-terminal) significantly stabilizes the α-helix over the 310-helix. Thus, the statistics that there are more shortest α-helices than 310-helices of the same length can be understood. It has been also found that the C-terminal of the shortest α-helix tends to end with a β-turn structure.

Key words: α-Helix, 310-Helix, Density functional theory(DFT) calculation, H-bond capping

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