多肽中氢键强度的理论研究

Theoretical Study on the Hydrogen Bond Strength in Polypeptide Molecules

用 B3 LYP/6-3 1 G* 方法优化了多肽分子的几何构型 ,计算了各个构型的电荷分布和氢键酸度 ,进而对多肽分子中的氢键强度进行了研究 .结果表明 ,多肽分子中氢键的强度同时取决于形成氢键的 H…O原子间距 R和 N—H… O之间的键角 β;多肽分子倾向于形成 R值小、β值大的大环氢键 .3 1 0 螺旋结构的多肽分子中的氢键具有协同效应 ,分子越大 ,分子中氢键越多 ,氢键的协同效应越强 .

The geometrical structures of tetrapeptide,and octapeptide complexes were optimized with B3LYP method. The hydrogen bond strength was studied by using the hydrogen bond acidity. It was concluded that the hydrogen bond has a the biggest hydrogen bond strength in peptide molecules if it has the smallest H…O distance and the largest N—H…O angle. It is intrinsic for the polypeptide to form the hydrogen bond,which has a smaller distance of H…O,a larger angle of N—H…O,and a bigger membered ring. There does exist the cooperativity among the hydrogen bonds in the 3_ 10 helix structure of peptides. The more the numbers of the hydrogen bonds in the helix structure,the stronger each hydrogen bond is. [WT5HZ]