Cooperative hydrogen-bonding in models of antiparallel β-sheets
Cooperative hydrogen-bonding in models of antiparallel β-sheets
复制标题
DOI：
10.1021/jp047404o
复制
发表时间：
2004-10-21
影响因子：
2.9
通讯作者：
Dannenberg, JJ
中科院分区：
文献类型：
--
作者：
Viswanathan, R;Asensio, A;Dannenberg, JJ
我们在B3LYP/D95(d，p)水平上对由两个或四个甘氨酸残基组成的反平行β-折叠模型和由两个亚甲基分隔的两个甘氨酸残基或四个甘氨酸残基组成的人工尼龙状两链或四链模型进行了全几何优化密度泛函理论计算。与α-螺旋中的氢键和氢键酰胺链中的氢键不同，聚甘氨酸链的缔合几乎没有或几乎没有氢键协同作用。我们发现，C-5链内氢键在形成链间氢键时被破坏或增强，这取决于甘氨酸(但不是尼龙样)结构中的氢键模式。在聚甘氨酸的β-折叠模型中，明显的氢键协作性的缺乏来自于这些链内氢键的减弱和加强。当尼龙链(不能形成链内氢键)形成两股和四股片状时，就会发生正常的协同氢键。与先前报道的关于α-螺旋结构的类似计算相比，氢键相互作用更强，氢键距离更短(平均而言)，这与观察到的淀粉样疾病，如阿尔茨海默病和普里子病，涉及a-螺旋二级结构到(可能更稳定的)β-折叠的转换是一致的。
We present fully geometrically optimized density functional theory calculations at the B3LYP/D95(d,p) level on antiparallel beta-sheet models consisting of two or four strands of two or four glycine residues and artificial nylon-like two- or four-strand models of two glycine residues separated by two methylene groups. Unlike the H-bonds in alpha-helices and chains of H-bonding amides, the association of polyglycine strands shows little or no H-bond cooperativity. We show that C-5 intrastrand H-bonds are either disrupted or enhanced upon formation of interstrand H-bonds, depending upon the H-bonding pattern in the glycine (but not the nylon-like) structures. The apparent relative absence of H-bond cooperativity in beta-sheet models of polyglycine derives from the weakening and strengthening of these intrastrand H-bonds. Normal cooperative H-bonding occurs when the nylon-like strands (which cannot form the intrastrand H-bond) form two- and four-strand sheets. The H-bonding interactions are stronger and the H-bonding distances shorter (on average) than previously reported for similar calculations on alpha-helical structures, consistent with the observations that amyloid diseases, such as Alzheimer's and prion diseases, involve conversion of a-helical secondary structures to (presumably more stable) beta-sheets.