Kinetic and crystallographic studies on 2-(β-D-glucopyranosyl)-5-methyl-1,3,4-oxadiazole, -benzothiazole, and -benzimidazole, inhibitors of muscle glycogen phosphorylase b.: Evidence for a new binding site
Kinetic and crystallographic studies on 2-(β-D-glucopyranosyl)-5-methyl-1,3,4-oxadiazole, -benzothiazole, and -benzimidazole, inhibitors of muscle glycogen phosphorylase b.: Evidence for a new binding site
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DOI：
10.1110/ps.041216105
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发表时间：
2005-04-01
期刊：
影响因子：
8
通讯作者：
Oikonomakos, NG
中科院分区：
文献类型：
--
作者：
Chrysina, ED;Kosmopoulou, MN;Oikonomakos, NG
为了确定能够设计对糖原磷酸化酶(GP)具有更高亲和力的抑制剂，从而控制2型糖尿病患者的高血糖，对三个新的类似物-β-D-葡萄糖苷、2-(β-D-吡喃葡萄糖基)-5-甲基-1、3，4-恶二唑、-苯并噻唑和-苯并咪唑的抑制GPB活性进行了评估。化合物对底物Glc-1-P表现出竞争性抑制，K分别为145.2(+/-11.6)、76(+/-4.8)和8.6(+/-0.7)µM。为了确定这种抑制作用的机理，我们进行了结晶学研究，并在高分辨率下测定了三个类似物(GPB-甲基恶二唑配合物，1.92埃；GPB-苯并噻唑，2.10埃；GPB-苯并咪唑，1.93埃)的结构。复杂的结构表明，抑制剂可以在三级结构变化很小的情况下被吸附在T-态GPB的催化位置上，这为理解抑制剂的效力变化提供了合理的依据。此外，苯并咪唑结合在新的变构抑制剂或吲哚结合部位，位于亚基界面的中央空腔区域，也结合在一个新的结合部位，位于蛋白质表面，远离(类似于32埃)其他结合部位，主要由Phe202、Tyr203、Val221和Phe252的非极性基团主导。
In an attempt to identify leads that would enable the design of inhibitors with enhanced affinity for glycogen phosphorylase (GP), that might control hyperglycaemia in type 2 diabetes, three new analogs of beta-D-glucopyranose, 2-(beta-D-glucopyranosyl)-5-methyl-1, 3, 4-oxadiazole, -benzothiazole, and -benzimidazole were assessed for their potency to inhibit GPb activity. The compounds showed competitive inhibition (with respect to substrate Glc-1-P) with K; values of 145.2 (+/- 11.6), 76 (+/- 4.8), and 8.6 (+/- 0.7) mu M, respectively. In order to establish the mechanism of this inhibition, crystallographic studies were carried out and the structures of GPb in complex with the three analogs were determined at high resolution (GPb-methyloxadiazole complex, 1.92 angstrom; GPb-benzothiazole, 2.10 angstrom; GPb-benzimidazole, 1.93 angstrom). The complex structures revealed that the inhibitors can be accommodated in the catalytic site of T-state GPb with very little change of the tertiary structure, and provide a rationalization for understanding variations in potency of the inhibitors. In addition, benzimidazole bound at the new allosteric inhibitor or indole binding site, located at the subunit interface, in the region of the central cavity, and also at a novel binding site, located at the protein surface, far removed (similar to 32 angstrom) from the other binding sites, that is mostly dominated by the nonpolar groups of Phe202, Tyr203, Val221, and Phe252.