Kuttel Michelle M, Naidoo Kevin J
Department of Chemistry, University of Cape Town, Cape Town, South Africa.
J Phys Chem B. 2005 Apr 21;109(15):7468-74. doi: 10.1021/jp044756m.
We present a potential of mean force surface for rotation about phi and psi dihedral angles of the alpha(1 --> 4)-glycosidic linkage in the maltose disaccharide (4-O-alpha-d-glucopyranosyl-d-glucopyranose) in aqueous solution. Comparison of the vacuum and solution free energy surfaces for maltose shows the principal effects of water to be an increase in the rotational freedom of the alpha(1 --> 4) linkage brought about by lowering the energy barrier for syn to anti conformational changes as well as expansion of the range of low-energy phi,psi conformations. This free energy analysis thus provides a thermodynamic and conformational rationale for the effects of water on alpha(1 --> 4)-linked polysaccharides and carbohydrate glasses.
我们展示了麦芽糖二糖（4-O-α-D-吡喃葡萄糖基-D-吡喃葡萄糖）中α(1→4)-糖苷键围绕φ和ψ二面角旋转的平均力势面。麦芽糖在真空和溶液中的自由能面比较表明，水的主要作用是通过降低顺式到反式构象变化的能垒以及扩大低能φ、ψ构象的范围，增加α(1→4)键的旋转自由度。因此，这种自由能分析为水对α(1→4)连接的多糖和碳水化合物玻璃的影响提供了热力学和构象方面的理论依据。
