银耳多糖对淀粉消化酶的抑制作用及其机理研究

目的:研究银耳多糖对胰α-淀粉酶和α-葡萄糖苷酶的抑制作用及机制。方法:以干银耳为原料，分别采用碱法提取、酶法脱蛋白和柱层析分离，得到总糖含量为92.45%的银耳多糖（Tremella fuciformis polysaccharide，TP），采用可见光分光光度法分析了TP对胰α-淀粉酶和α-葡萄糖苷酶的抑制作用，采用荧光光谱法和圆二色谱法表征了TP对该两种酶结构的影响。结果:TP能抑制该两种酶的活性，其对胰α-淀粉酶的抑制作用明显高于α-葡萄糖苷酶，对该两种酶的半抑制浓度（IC₅₀）分别为7.6835和16.9306 mg/mL。TP通过与该两种淀粉消化酶发生相互作用抑制其活性。TP与胰α-淀粉酶相互作用明显，可静态猝灭此酶，改变其二级结构；TP与α-葡萄糖苷酶相互作用微弱，不能改变其二级结构。结论:TP通过与淀粉消化酶发生相互作用抑制其活性。

Inhibitory Effect of Tremella fuciformis Polysaccharide on Starch Digestive Enzymes and Its Action Mechanism

Objective: To investigate the inhibitory effect of Tremella fuciformis polysaccharide (TP) on pancreatic α-amylase and α-glucosidase and its action mechanism. Methods: TP with a total sugar content of 92.45% was obtained by alkaline extraction from dried Tremella fuciformis, enzymatic deproteinization and column chromatography separation in turn. The inhibitory effect of TP on pancreatic α-amylase and α-glucosidase was measured by visible spectrophotometry, and its action on the structures of these two enzymes was characterized by fluorescence spectrometry and circular dichroism. Results: TP could inhibit the activities of these two enzymes, and its inhibition on pancreatic α-amylase was significantly higher than that on α-glucosidase, and its half inhibitory concentrations (IC₅₀) on these two enzymes were 7.6835 and 16.9306 mg/mL, respectively. TP inhibited the activity of the enzymes by interacting with them. TP interacted strongly with pancreatic α-amylase. It could statically quench pancreatic α-amylase and change its secondary structure. However, TP interacted weakly with α-glucosidase and could not change its secondary structure. Conclusion: TP inhibited the activity of starch-digestive enzymes by interacting with them.