1xkx

Kinetic and crystallographic studies on 2-(beta-D-glucopyranosyl)-5-methyl-1,3,4-oxadiazole,-benzothiazole, and-benzimidazole, inhibitors of muscle glycogen phosphorylase b. Evidence for a new binding site.

spinqualitylabelsall models 1xkx, resolution 1.93Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1xkx is a 1 chain structure with sequence from Oryctolagus cuniculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.93Å Ligands: IMK, PLP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PYGM_RABIT Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Enzymes from different sources differ in their regulatory mechanisms and in their natural substrates. However, all known phosphorylases share catalytic and structural properties. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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(i) values of 145.2 (+/-11.6), 76 (+/-4.8), and 8.6 (+/-0.7) muM, 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-methyl-oxadiazole complex, 1.92 A; GPb-benzothiazole, 2.10 A; GPb-benzimidazole, 1.93 A). 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 (approximately 32 A) from the other binding sites, that is mostly dominated by the nonpolar groups of Phe202, Tyr203, Val221, and Phe252. Kinetic and crystallographic studies on 2-(beta-D-glucopyranosyl)-5-methyl-1, 3, 4-oxadiazole, -benzothiazole, and -benzimidazole, inhibitors of muscle glycogen phosphorylase b. Evidence for a new binding site.,Chrysina ED, Kosmopoulou MN, Tiraidis C, Kardakaris R, Bischler N, Leonidas DD, Hadady Z, Somsak L, Docsa T, Gergely P, Oikonomakos NG Protein Sci. 2005 Apr;14(4):873-88. Epub 2005 Mar 1. PMID:15741340 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glycogen phosphorylase 3D structures

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