1kck | pdb_00001kck

Bacillus circulans strain 251 Cyclodextrin glycosyl transferase mutant N193G

spinqualitylabelsall models 1kck, resolution 2.43Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1kck is a 1 chain structure with sequence from Niallia circulans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.43Å Ligands: ADH, BGC, CA, G6D, GLC, PRD_900001, PRD_900009, PRD_900065 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CDGT2_NIACI 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 Cyclodextrin-glycosyltransferase (CGTase) catalyzes the formation of alpha-, beta-, and gamma-cyclodextrins (cyclic alpha-(1,4)-linked oligosaccharides of 6, 7, or 8 glucose residues, respectively) from starch. Nine substrate binding subsites were observed in an x-ray structure of the CGTase from Bacillus circulans strain 251 complexed with a maltononaose substrate. Subsite -6 is conserved in CGTases, suggesting its importance for the reactions catalyzed by the enzyme. To investigate this in detail, we made six mutant CGTases (Y167F, G179L, G180L, N193G, N193L, and G179L/G180L). All subsite -6 mutants had decreased k(cat) values for beta-cyclodextrin formation, as well as for the disproportionation and coupling reactions, but not for hydrolysis. Especially G179L, G180L, and G179L/G180L affected the transglycosylation activities, most prominently for the coupling reactions. The results demonstrate that (i) subsite -6 is important for all three CGTase-catalyzed transglycosylation reactions, (ii) Gly-180 is conserved because of its importance for the circularization of the linear substrates, (iii) it is possible to independently change cyclization and coupling activities, and (iv) substrate interactions at subsite -6 activate the enzyme in catalysis via an induced-fit mechanism. This article provides for the first time definite biochemical evidence for such an induced-fit mechanism in the alpha-amylase family. The remote substrate binding subsite -6 in cyclodextrin-glycosyltransferase controls the transferase activity of the enzyme via an induced-fit mechanism.,Leemhuis H, Uitdehaag JC, Rozeboom HJ, Dijkstra BW, Dijkhuizen L J Biol Chem. 2002 Jan 11;277(2):1113-9. Epub 2001 Nov 5. PMID:11696539 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glycosyltransferase 3D structures

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