Inhibitory mechanism of two allosteric inhibitors, oleanolic acid and ursolic acid on α-glucosidase
Inhibitory mechanism of two allosteric inhibitors, oleanolic acid and ursolic acid on α-glucosidase
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DOI：
10.1016/j.ijbiomac.2017.10.040
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发表时间：
2018-02-01
影响因子：
8.2
通讯作者：
Gong, Deming
中科院分区：
文献类型：
--
作者：
Ding, Huafang;Hu, Xing;Gong, Deming
通过抑制α-葡萄糖苷酶活性来有效调节血糖控制是治疗糖尿病的有效方法。研究了油酸和熊果酸对α-葡萄糖苷酶的抑制动力学及机理。油酸和熊果酸表现出强的抑制活性，其IC 50值分别为（6.35 +/- 0.02）x 10（-6）和（1.69 +/- 0.03）x 10（-5）mol L-1，并且是可逆的和非竞争性的。它们与α-葡萄糖苷酶结合后，均引起α-葡萄糖苷酶构象变化和内源荧光猝灭。在298 K时，齐墩果酸和熊果酸与α-葡萄糖苷酶的结合常数分别为（2.04 +/- 0.02）× 10（3）和（1.87 +/- 0.02）× 10（3）Lmol（-1）。对接结果表明，齐墩果酸和熊果酸分别结合在α-葡萄糖苷酶的第2和第4腔的不同变构位点，引发了变构调节，扰乱了α-葡萄糖苷酶的构象动力学，最终导致酶的催化活性下降。由于形成了油酸-或熊果酸-α-葡糖苷酶-底物的非反应性三元复合物，底物不被α-葡糖苷酶催化产生进一步的产物。油酸和熊果酸的组合显示出对α-葡萄糖苷酶的显著协同抑制作用。(C)2017爱思唯尔B. V.保留所有权利。
Glycemic control which can be efficaciously regulated by inhibiting a-glucosidase activity is an effective therapy for diabetes mellitus. This work is to investigate the kinetics and inhibition mechanism of oleanolic acid and ursolic acid on alpha-glucosidase. Oleanolic acid and ursolic acid exhibited potent inhibitory activities with IC50 values of (6.35 +/- 0.02) x 10(-6) and (1.69 +/- 0.03) x 10(-5) mol L-1 respectively in a reversible and non-competitive manner. Both of them binding to alpha-glucosidase induced the conformational change and intrinsic fluorescence quenching of alpha-glucosidase. The binding constants of oleanolic acid and ursolic acid with alpha-glucosidase at 298 K were (2.04 +/- 0.02) x 10(3) and (1.87 +/- 0.02) x 10(3) Lmol(-1), respectively. Docking results showed that oleanolic acid and ursolic acid bound in different allosteric sites of cavity 2 and cavity 4 on alpha-glucosidase, respectively, which triggered allosteric regulation to perturb conformational dynamics of alpha-glucosiciase, eventually leading to a decrease of catalytic activity of the enzyme. The substrate was not catalyzed by alpha-glucosidase to generate further products due to formation of a nonreactive ternary complex of oleanolic acid- or ursolic acid-alpha-glucosidase-substrate. The combination of oleanolic acid and ursolic acid displayed a significant synergistic inhibition on alpha-glucosidase. (C) 2017 Elsevier B.V. All rights reserved.