Department of Life Sciences, University of Trieste, Trieste, Italy.
J Phys Chem B. 2012 Sep 27;116(38):11701-11. doi: 10.1021/jp303910u. Epub 2012 Sep 13.
Molecular dynamics simulations were carried out on several systems of caffeine interacting with simple sugars. These included a single caffeine molecule in a 3 m solution of α-D-glucopyranose, at a caffeine concentration of 0.083 m, a single caffeine in a 3 m solution of β-D-glucopyranose, and a single caffeine molecule in a 1.08 m solution of sucrose (table sugar). Parallel nuclear magnetic resonance titration experiments were carried out on the same solutions under similar conditions. Consistent with previous thermodynamic experiments, the sugars were found to have an affinity for the caffeine molecules in both the simulations and experiments, and the binding in these complexes occurs by face-to-face stacking of the hydrophobic triad of protons of the pyranose rings against the caffeine face, rather than by hydrogen bonding. For the disaccharide, the binding occurs via stacking of the glucose ring against the caffeine, with a lesser affinity for the fructose observed. These findings are consistent with the association being driven by hydrophobic hydration and are similar to the previously observed binding of glucose rings to various other planar molecules, including indole, serotonin, and phenol.
对咖啡因与单糖相互作用的几个体系进行了分子动力学模拟。这些体系包括在 3 m 的α-D-吡喃葡萄糖溶液中、咖啡因浓度为 0.083 m 的单个咖啡因分子，在 3 m 的β-D-吡喃葡萄糖溶液中单个咖啡因分子，以及在 1.08 m 的蔗糖（食糖）溶液中单个咖啡因分子。在相同条件下对相同溶液进行了平行核磁共振滴定实验。与先前的热力学实验一致，发现这些糖在模拟和实验中都对咖啡因分子具有亲和力，并且这些配合物中的结合是通过吡喃糖环的疏水性三联体质子与咖啡因面的面对面堆叠发生的，而不是通过氢键。对于二糖，结合是通过葡萄糖环与咖啡因堆叠发生的，观察到对果糖的亲和力较小。这些发现与由疏水性水合作用驱动的缔合一致，并且与先前观察到的葡萄糖环与各种其他平面分子（包括吲哚、血清素和苯酚）的结合相似。
