College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China.
Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UA, UK.
Food Chem. 2019 Jun 15;283:468-474. doi: 10.1016/j.foodchem.2019.01.087. Epub 2019 Jan 19.
The binding interactions between young apple polyphenols and porcine pancreatic α-amylase were investigated through isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) and molecular docking. The results obtained were compared with those obtained through inhibition kinetics and fluorescence quenching. It was found that binding of tannic acid, chlorogenic acid, caffeic acid and epicatechin with α-amylase is an exothermal process, with the binding constants in the order of tannic acid > chlorogenic acid > caffeic acid > epicatechin. This is consistent with the orders of reciprocal of competitive inhibition constant and fluorescence quenching constant. The binding energy obtained through molecular docking showed the same order, except for epicatechin. These results are consistent with the inhibition of α-amylase being caused by the binding of the polyphenols with the enzyme. In addition, from the fluorescence quenching and DSC data, total polyphenols, tannic acid, chlorogenic acid and caffeic acid were found to partially unfold the enzyme structure.
采用等温滴定量热法（ITC）、差示扫描量热法（DSC）和分子对接技术研究了幼龄苹果多酚与猪胰腺α-淀粉酶之间的结合相互作用。并将所得结果与抑制动力学和荧光猝灭法的结果进行了比较。结果表明，单宁酸、绿原酸、咖啡酸和表儿茶素与α-淀粉酶的结合是一个放热过程，其结合常数的顺序为单宁酸＞绿原酸＞咖啡酸＞表儿茶素。这与竞争性抑制常数和荧光猝灭常数的倒数顺序一致。通过分子对接获得的结合能也表现出相同的顺序，除了表儿茶素。这些结果与多酚与酶结合导致α-淀粉酶抑制的结果一致。此外，从荧光猝灭和 DSC 数据来看，总多酚、单宁酸、绿原酸和咖啡酸部分使酶结构展开。
