1kcl

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{{STRUCTURE_1kcl| PDB=1kcl | SCENE= }}
{{STRUCTURE_1kcl| PDB=1kcl | SCENE= }}
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'''Bacillus ciruclans strain 251 Cyclodextrin glycosyl transferase mutant G179L'''
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===Bacillus ciruclans strain 251 Cyclodextrin glycosyl transferase mutant G179L===
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==Overview==
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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.
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(as it appears on PubMed at http://www.pubmed.gov), where 11696539 is the PubMed ID number.
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{{ABSTRACT_PUBMED_11696539}}
==About this Structure==
==About this Structure==
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[[Category: Glycosyltransferase]]
[[Category: Glycosyltransferase]]
[[Category: Transferase]]
[[Category: Transferase]]
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Revision as of 07:07, 2 July 2008

Template:STRUCTURE 1kcl

Bacillus ciruclans strain 251 Cyclodextrin glycosyl transferase mutant G179L

Template:ABSTRACT PUBMED 11696539

About this Structure

1KCL is a Single protein structure of sequence from Bacillus circulans. Full crystallographic information is available from OCA.

Reference

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

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