Jöbstl Elisabeth, Howse Jonathan R, Fairclough J Patrick A, Williamson Mike P
Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
J Agric Food Chem. 2006 Jun 14;54(12):4077-81. doi: 10.1021/jf053259f.
Interaction of the tea polyphenol epigallocatechin gallate (EGCG) with beta-casein in milk affects the taste of tea and also affects the stability of the tea and the antioxidant ability of the EGCG. In addition, interaction of polyphenols with the chemically similar salivary proline-rich proteins is largely responsible for the astringency of tea and red wine. With the use of single molecule force microscopy, we demonstrate that the interaction of EGCG with a single casein molecule is multivalent and leads to reduction in the persistence length of casein as calculated using the wormlike chain model and a reduction in its radius of gyration. The extra force required to stretch casein in the presence of EGCG is largely entropic, suggesting that multivalent hydrophobic interactions cause a compaction of the casein micelle.
茶中的茶多酚表没食子儿茶素没食子酸酯（EGCG）与牛奶中的β-酪蛋白相互作用，会影响茶的口感，还会影响茶的稳定性以及EGCG的抗氧化能力。此外，多酚与化学结构相似的富含脯氨酸的唾液蛋白之间的相互作用，在很大程度上导致了茶和红酒的涩味。通过单分子力显微镜，我们证明EGCG与单个酪蛋白分子的相互作用是多价的，并且会导致酪蛋白的持久长度（使用蠕虫状链模型计算）减小以及其回转半径减小。在EGCG存在的情况下拉伸酪蛋白所需的额外力在很大程度上是熵力，这表明多价疏水相互作用会导致酪蛋白胶束压缩。
