Centre for Nutrition and Food Sciences, ARC Centre of Excellence in Plant Cell Walls, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
Centre for Nutrition and Food Sciences, ARC Centre of Excellence in Plant Cell Walls, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia; Quadram Institute Biosciences, Norwich Research Park, Norwich NR4 7UA, UK.
Food Chem. 2018 Aug 30;258:164-173. doi: 10.1016/j.foodchem.2018.03.017. Epub 2018 Mar 7.
The effects of tea polyphenols on binding of porcine pancreatic α-amylase (PPA) with normal maize starch granules were studied through solution depletion assays, fluorescence spectroscopy and initial rate kinetics. Only polyphenols which have inhibitory activity against PPA increased the binding of PPA with starch. The results are consistent with a binding equilibrium between polyphenols, starch and PPA. The dissociation constant (K) for PPA binding was decreased by tea polyphenols, with the effects greater for theaflavins than catechins and for galloylated than non-galloylated polyphenols. Tea polyphenols were also shown to increase the binding rate of PPA to starch. In addition, there were positive linear correlations between 1/K and reciprocal of competitive inhibition constant (1/K) and between 1/K and fluorescence quenching constant (K). Despite the greater amount of PPA on the granules, starch hydrolysis is reduced because the polyphenol inhibition of PPA persists after binding to starch.
通过溶液耗竭实验、荧光光谱法和初始速率动力学研究了茶多酚对猪胰腺α-淀粉酶（PPA）与正常玉米淀粉颗粒结合的影响。只有对 PPA 具有抑制活性的多酚才会增加 PPA 与淀粉的结合。结果与多酚、淀粉和 PPA 之间的结合平衡一致。多酚降低了 PPA 结合的解离常数（K），茶黄素的作用大于儿茶素，没食子酰化多酚大于非没食子酰化多酚。研究还表明，茶多酚会增加 PPA 与淀粉的结合速率。此外，1/K 与竞争抑制常数（1/K）的倒数以及 1/K 与荧光猝灭常数（K）之间呈正线性相关。尽管颗粒上的 PPA 量更多，但由于结合到淀粉后多酚对 PPA 的抑制作用持续存在，淀粉水解减少。
