3cgt: Difference between revisions
New page: left|200px<br /><applet load="3cgt" size="450" color="white" frame="true" align="right" spinBox="true" caption="3cgt, resolution 2.4Å" /> '''STRUCTURE OF CYCLODEX... |
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[[Image:3cgt.jpg|left|200px]]<br /><applet load="3cgt" size=" | [[Image:3cgt.jpg|left|200px]]<br /><applet load="3cgt" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="3cgt, resolution 2.4Å" /> | caption="3cgt, resolution 2.4Å" /> | ||
'''STRUCTURE OF CYCLODEXTRIN GLYCOSYLTRANSFERASE COMPLEXED WITH ITS MAIN PRODUCT BETA-CYCLODEXTRIN'''<br /> | '''STRUCTURE OF CYCLODEXTRIN GLYCOSYLTRANSFERASE COMPLEXED WITH ITS MAIN PRODUCT BETA-CYCLODEXTRIN'''<br /> | ||
==Overview== | ==Overview== | ||
Crystals of the inactive mutant Glu257-->Ala of cyclodextrin | Crystals of the inactive mutant Glu257-->Ala of cyclodextrin glycosyltransferase were soaked with the cyclodextrin (CD) derivative S-(alpha-D-glucopyranosyl)-6-thio-beta-CD. The structural analysis showed its beta-CD moiety with no density indication for the exocyclic glucosyl unit. For steric reasons, however, the position of this unit is restricted to be at only two of the seven glucosyl groups of beta-CD. The analysis indicated that the enzyme can cyclize branched alpha-glucans. The ligated beta-CD moiety revealed how the enzyme binds its predominant cyclic product. The conformation of the ligated beta-CD was intermediate between the more symmetrical conformation in beta-CD dodecahydrate crystals and the conformation of a bound linear alpha-glucan chain. Its scissile bond was displaced by 2.8 A from the position in linear alpha-glucans. Accordingly, the complex represents the situation after the cyclization reaction but before diffusion into the solvent, where a more symmetrical conformation is assumed, or the equivalent state in the reverse reaction. Furthermore, a unifying nomenclature for oligosaccharide-binding subsites in proteins is proposed. | ||
==About this Structure== | ==About this Structure== | ||
3CGT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_circulans Bacillus circulans] with BCD and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cyclomaltodextrin_glucanotransferase Cyclomaltodextrin glucanotransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.19 2.4.1.19] Full crystallographic information is available from [http:// | 3CGT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_circulans Bacillus circulans] with <scene name='pdbligand=BCD:'>BCD</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cyclomaltodextrin_glucanotransferase Cyclomaltodextrin glucanotransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.19 2.4.1.19] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CGT OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Cyclomaltodextrin glucanotransferase]] | [[Category: Cyclomaltodextrin glucanotransferase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Schmidt, A | [[Category: Schmidt, A K.]] | ||
[[Category: Schulz, G | [[Category: Schulz, G E.]] | ||
[[Category: BCD]] | [[Category: BCD]] | ||
[[Category: CA]] | [[Category: CA]] | ||
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[[Category: starch degradation]] | [[Category: starch degradation]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:08:44 2008'' | ||
Revision as of 20:08, 21 February 2008
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STRUCTURE OF CYCLODEXTRIN GLYCOSYLTRANSFERASE COMPLEXED WITH ITS MAIN PRODUCT BETA-CYCLODEXTRIN
OverviewOverview
Crystals of the inactive mutant Glu257-->Ala of cyclodextrin glycosyltransferase were soaked with the cyclodextrin (CD) derivative S-(alpha-D-glucopyranosyl)-6-thio-beta-CD. The structural analysis showed its beta-CD moiety with no density indication for the exocyclic glucosyl unit. For steric reasons, however, the position of this unit is restricted to be at only two of the seven glucosyl groups of beta-CD. The analysis indicated that the enzyme can cyclize branched alpha-glucans. The ligated beta-CD moiety revealed how the enzyme binds its predominant cyclic product. The conformation of the ligated beta-CD was intermediate between the more symmetrical conformation in beta-CD dodecahydrate crystals and the conformation of a bound linear alpha-glucan chain. Its scissile bond was displaced by 2.8 A from the position in linear alpha-glucans. Accordingly, the complex represents the situation after the cyclization reaction but before diffusion into the solvent, where a more symmetrical conformation is assumed, or the equivalent state in the reverse reaction. Furthermore, a unifying nomenclature for oligosaccharide-binding subsites in proteins is proposed.
About this StructureAbout this Structure
3CGT is a Single protein structure of sequence from Bacillus circulans with and as ligands. Active as Cyclomaltodextrin glucanotransferase, with EC number 2.4.1.19 Full crystallographic information is available from OCA.
ReferenceReference
Structure of cyclodextrin glycosyltransferase complexed with a derivative of its main product beta-cyclodextrin., Schmidt AK, Cottaz S, Driguez H, Schulz GE, Biochemistry. 1998 Apr 28;37(17):5909-15. PMID:9558324
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