摘要
本文应用紫外、荧光、圆二色谱和分子模拟等手段,分析测定了大黄酸对α-淀粉酶的抑制作用、抑制类型和抑制动力学常数,探讨了大黄酸对α-淀粉酶二级结构的影响,并通过分子模拟软件对大黄酸和α-淀粉酶进行分子对接。结果表明,大黄酸是一种可逆的竞争型α-淀粉酶抑制剂,其半抑制率IC50为0.43±0.02 m M,抑制常数Ki为0.35±0.03 m M;进一步的圆二色谱分析表明,大黄酸能使α-淀粉酶二级结构含量的变化(α-螺旋含量由12.22%逐渐增加到22.72%,β-折叠含量由43.24%逐渐降低到36.43%),这意味着大黄酸能够诱导α-淀粉酶的构象发生部分改变;螯合钙离子实验证实了大黄酸能够螯合活性中心的钙离子;分子模拟结果也表明,大黄酸能够优先结合到α-淀粉酶的活性中心,并与催化基团TRP59和TYR62发生相互作用,形成氢键和π-π效应,进而与淀粉竞争活性中心,从而降低了α-淀粉酶的催化活性。
The inhibitory effect（including inhibitory mechanism, type and kinetic parameters） of rhein on α-amylase and the effect on α-amylase secondary structure were investigated by UV, fluorescence, and circular dichroism spectrometry, while molecular docking of rhein and α-amylase was conducted by molecular simulation. The results showed that rhein was a reversible and competitive inhibitor to α-amylase. The half-maximal inhibitory concentration（IC50） and inhibition constant（Ki） were 0.43 ± 0.02 m M and 0.35 ± 0.03 m M, respectively. Circular dichroism spectra analysis revealed that rhein could alter the content of secondary structure in α-amylase（gradual increase of α-helix content from 12.22% to 22.72% and gradual decrease of β-sheet from 43.24% to 36.43%）, indicating that rhein could induce partial conformational changes in α-amylase. Chelating calcium ions experiment indicated that rhein combined with calcium ions at the α-amylase active site. Moreover, the results of molecular simulation indicated that rhein had a binding preference for the α-amylase active site, interacting with the catalytic groups TRP59 and TYR62 by forming hydrogen bonds and π-π interaction. Furthermore, rhein competed with starch, consequently reducing the catalytic activity of α-amylase.
出处
《现代食品科技》
EI
CAS
北大核心
2015年第2期47-51,共5页
Modern Food Science and Technology
基金
国家自然科学基金资助项目(81360205)
关键词
大黄酸
Α-淀粉酶
抑制作用
二级结构
分子模拟
rhein
α-amylase
inhibitory effect
secondary structure
molecular simulation
