红茶和绿茶与人唾液α-淀粉酶相互作用的酶促反应动力学研究

目的：旨在研究红茶和绿茶多酚对人唾液α-淀粉酶（human salivaryα-amylase,HSA）的抑制作用。方法：在37℃和pH6.9条件下,进行HSA催化水解淀粉的反应。在不间断540nm波长下,获得麦芽糖的吸光率。通过Lineweaver-Burk图计算催化参数（Vmax和Ks）,并统计分析和判断抑制类型。结果：红茶、绿茶与无抑制剂的最大反应速度（Vmax）及之间的差异均具有统计学意义（P〈0.05）,无抑制剂和绿茶抑制剂的酶-底物解离常数（Ks）之间的差异具有统计学意义（P〈0.05）。红茶抑制剂解离常数（Ki）值小于绿茶（P〈0.05）。根据统计学分析,红茶抑制为非竞争性抑制型,绿茶抑制为反竞争性抑制型。结论：体外实验证实红茶比绿茶抑制HSA的作用强,生成的复合物也相对比较稳定。故在生活中饮用红茶者,会产生较强的黏膜收敛性的感觉,导致色素易于沉积在牙齿表面。

Interaction between Black/Green Tea and α-Amylase from Human Saliva by Kinetics of Enzyme-Catalyzed Reactions

Objective：To study the inhibitory effects ofα-amylase from human saliva by black/green tea polyphenols.Methods：The reactions of HSA-catalyzed the hydrolysis of starch were carried out with or without the inhibitor of black tea or green tea at 37℃and pH 6.9.Then the absorbance of maltose was measured continuously at 540nm.The catalytic parameters（Vmaxand Ks）were calculated using Lineweaver-Burk plots,and the type of inhibition was determined by statistical analysis.Results：There were significant differences among the maximum velocity（Vmax）in absence and presence of black/green tea inhibitors（P0.05）,and between the dissociation constants of enzyme-substrate（Ks）in the absence and presence of green tea inhibitor（P0.05）.The dissociation constant of enzyme-inhibitor（Ki）of green tea was higher than the one of black tea（P0.05）.According to the statistical analysis,the inhibitory patterns of black tea and green tea were noncompetitive and anticompetitive,respectively.Conclusion：Our studies have demonstrated that in vitro,the inhibitory effects ofα-amylase from human saliva by black tea polyphenols were stronger than that of green tea polyphenols,and the complex of black tea was more stable than that of green tea.The results suggest that it is much easier to bring the oral sensation of astringency and the stain deposites on the teeth surfaces for beverages of black tea.