Abstract：
Resistant starch (RS) is important in controlling diabetes. The primary objective of this study is to examine the impact of molecular conformation on the enzymatic hydrolysis efficiency of starch by α-amylase. And the interactions between starch molecules with different conformations and α-amylase were analysed by using molecule dynamics simulation and molecular docking. It was found, the natural conformational starch molecule was hydrolysed from the middle of the starch chain by α-amylase, producing polysaccharides. The bent PS-conformational starch molecules with multiple O2-O3 intramolecular hydrogen bonds produced by high-pressure was hydrolysed from the head of the starch chain to produce glucose, which is not conducive to RS formation. The stretched H-conformation without intramolecular hydrogen bonds produced by heat treatment was not hydrolysed by α-amylase. However, it occupied the active groove and formed strong interactions with α-amylase, which prevented other starch molecules from binding to α-amylase, thus reducing hydrolysis efficiency. Moreover, the total interaction energies between the three starch molecules and α-amylase were approximately 78 kJ/mol. And several hydrogen bonds were formed between the starch molecules and α-amylase, which provides evidence for the continuous sliding hydrolysis hypothesis of α-amylase. Moreover, these results provide an important reference for elucidating the mechanism of RS formation.
摘要：
抗性淀粉（RS）在控制糖尿病中很重要。本研究的主要目的是研究分子构象对α-淀粉酶酶解淀粉效率的影响。利用分子动力学模拟和分子对接分析了不同构象的淀粉分子与α-淀粉酶的相互作用。它被发现了,天然构象淀粉分子从淀粉链的中间被α-淀粉酶水解，生产多糖。高压产生的具有多个O2-O3分子内氢键的弯曲PS构象淀粉分子从淀粉链的头部水解产生葡萄糖,这不利于RS的形成。通过热处理产生的没有分子内氢键的拉伸H构象不会被α-淀粉酶水解。然而,它占据了活性沟，并与α-淀粉酶形成了强烈的相互作用，阻止其他淀粉分子与α-淀粉酶结合，从而降低水解效率。此外，三种淀粉分子与α-淀粉酶的总相互作用能约为78kJ/mol。淀粉分子和α-淀粉酶之间形成了几个氢键,这为α-淀粉酶的连续滑动水解假说提供了证据。此外，这些结果为阐明RS形成机制提供了重要参考。
