UMR 5255 ISM CESAMO, Université Bordeaux, CNRS, Talence, France.
Planta Med. 2011 Jul;77(11):1116-22. doi: 10.1055/s-0030-1270848. Epub 2011 Mar 16.
Astringency is a sensation in the mouth used in judging the quality of red wine. The rough, dry, and puckering sensation called astringency is the result of an interaction between tannins and saliva proteins, mainly proline-rich proteins (PRP), which leads to the formation and precipitation of a complex. A dry and rough sensation is then perceived in the mouth. To get an insight into astringency at the molecular level we investigated: (i) An efficient and iterative method for 4-8 procyanidin synthesis, which gives rise to all possible 4-8 procyanidins up to the tetramer with total control of degree of oligomerization and stereochemistry. (ii) The 3D-structural preferences, which take into account their internal movements, using 2D NMR and molecular modeling. (iii) The self-association process in water or hydroalcoholic solutions using diffusion NMR spectroscopy that gives the active proportion of tannins able to fix proteins. (iv) A comprehensive description of the PRP-procyanidin complex formation to get information about stoichiometry, binding site localization, and affinity constants for different procyanidins. The data collected suggest that the interactions are controlled by both procyanidin conformational and colloidal state preferences. All these results provide new insights into the molecular interpretation of tannin astringency.
涩味是口腔用来判断红酒质量的一种感觉。涩味是单宁和唾液蛋白（主要是富含脯氨酸的蛋白质，PRP）相互作用的结果，导致复合物的形成和沉淀。然后，口腔会感觉到干燥和粗糙的感觉。为了从分子水平深入了解涩味，我们研究了：（i）一种高效、迭代的 4-8 原花青素合成方法，该方法可以产生所有可能的 4-8 原花青素，直到四聚体，完全控制聚合度和立体化学。（ii）使用 2D NMR 和分子建模考虑其内部运动的 3D 结构偏好。（iii）使用扩散 NMR 光谱在水或水醇溶液中的自缔合过程，给出能够固定蛋白质的单宁的活性比例。（iv）对 PRP-原花青素复合物形成的全面描述，以获取有关不同原花青素的化学计量比、结合部位定位和亲和力常数的信息。收集的数据表明，相互作用受原花青素构象和胶体状态偏好的控制。所有这些结果为单宁涩味的分子解释提供了新的见解。
