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| [[Image:1cxe.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1cxe| PDB=1cxe | SCENE= }} | | {{STRUCTURE_1cxe| PDB=1cxe | SCENE= }} |
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| '''COMPLEX OF CGTASE WITH MALTOTETRAOSE AT ROOM TEMPERATURE AND PH 9.1 BASED ON DIFFRACTION DATA OF A CRYSTAL SOAKED WITH ALPHA-CYCLODEXTRIN'''
| | ===COMPLEX OF CGTASE WITH MALTOTETRAOSE AT ROOM TEMPERATURE AND PH 9.1 BASED ON DIFFRACTION DATA OF A CRYSTAL SOAKED WITH ALPHA-CYCLODEXTRIN=== |
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| ==Overview==
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| Asp-229, Glu-257, and Asp-328 constitute the catalytic residues in cyclodextrin glycosyl transferase from Bacillus circulans strain 251. Via site-directed mutagenesis constructed D229N, E257Q, and D328N mutant proteins showed a 4,000-60,000-fold reduction of cyclization activity. A D229N/E257Q double mutant showed a 700,000-fold reduction and was crystallized for use in soaking experiments with alpha-cyclodextrin. Crystal structures were determined of wild type CGTase soaked at elevated pH with alpha-cyclodextrin (resolution, 2.1 A) and maltoheptaose (2.4 A). In addition, structures at cryogenic temperature were solved of the unliganded enzyme (2.2 A) and of the D229N/E257Q mutant after soaking with alpha-cyclodextrin (2.6 A). In the crystals soaked in alpha-cyclodextrin and maltoheptaose, a maltotetraose molecule is observed to bind in the active site. Residue 229 is at hydrogen bonding distance from the C-6 hydroxyl group of the sugar, which after cleavage will contain the new reducing end. In the D229N/E257Q double mutant structure, two alpha-cyclodextrins are observed to replace two maltoses at the E-domain, thus providing structural information on product inhibition via binding to the enzyme's raw starch binding domain.
| | The line below this paragraph, {{ABSTRACT_PUBMED_7493956}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 7493956 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_7493956}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Strokopytov, B V.]] | | [[Category: Strokopytov, B V.]] |
| [[Category: Glycosyltransferase]] | | [[Category: Glycosyltransferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:13:02 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 21:42:49 2008'' |
