绿豆RS4·Se(Ⅳ)制备、结构表征及对酶活抑制动力学

Preparation and Structural Characterization of Mung Bean RS4·Se(Ⅳ) and Kinetics of Enzymatic Inhibition by It

以绿豆抗性淀粉(mung bean resistant starch,MB-RS4)为原料,通过硝酸-亚硒酸钠法制备硒化绿豆抗性淀粉(selenized mung bean resistant starch,MB-RS4·Se(IV));利用扫描电镜对比硒化前后表观形态发现硒化后淀粉颗粒完全塌陷并呈碎片化;通过紫外光谱、傅里叶变换红外光谱、X射线衍射、凝胶渗透色谱、核磁共振分析硒化前后结构特性,结果显示硒化后紫外特征峰发生红移和增色效应,在787.88、730.88 cm-1和654.75 cm-1波数处出现Se=O、C—C(Se)2和Se—O—C特征峰,结晶结构被破坏,分子质量显著减小,MB-RS4·Se(IV)构型翻转、C6位发生取代;同时体外对α-葡萄糖苷酶和α-淀粉酶抑制作用及酶促反应动力学分析,MB-RS4·Se(IV)对α-葡萄糖苷酶和α-淀粉酶抑制作用显著增强,酶促反应动力学结果表明对α-葡萄糖苷酶抑制作用为竞争性抑制,对α-淀粉酶抑制作用为混合型反竞争性抑制。

In this paper, selenized mung bean resistant starch(MB-RS4·Se(IV)) was prepared from mung bean resistant starch(MB-RS4) by the nitric acid-sodium selenite method. Scanning electron microscopy(SEM) revealed that the starch granules were completely collapsed and fragmented after selenization. The structural characteristics of MB-RS4 and MBRS4·Se(IV) were analyzed by ultraviolet(UV) spectroscopy, Fourier transform infrared(FTIR) spectroscopy, X-ray diffraction(XRD), gel permeation chromatography(GPC), and nuclear magnetic resonance(NMR). The results showed that selenization resulted in a red shift of the UV peak and a hyperchromic effect. Additionally, the characteristic peaks of Se=O, C–C(Se)2 and Se–O–C appeared at wavenumbers of 787.88, 730.88 and 654.75 cm, respectively, and the crystal structure was destroyed. The molecular mass dropped significantly, and MB-RS4·Se(IV)’s configuration was reversed and the C6 position was substituted compared with MB-RS4. MB-RS4·Se(IV) had a significantly enhanced inhibitory effect on α-glucosidase and α-amylase. The results of the enzymatic reaction kinetics showed that the inhibition of α-glucosidase was competitive type, and the inhibition of α-amylase was mixed anticompetitive type.