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| [[Image:1vfm.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1vfm| PDB=1vfm | SCENE= }} | | {{STRUCTURE_1vfm| PDB=1vfm | SCENE= }} |
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| '''Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase 2/alpha-cyclodextrin complex'''
| | ===Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase 2/alpha-cyclodextrin complex=== |
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| ==Overview==
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| Thermoactinomyces vulgaris R-47 alpha-amylase 2 (TVAII) has the unique ability to hydrolyze cyclodextrins (CDs), with various sized cavities, as well as starch. To understand the relationship between structure and substrate specificity, x-ray structures of a TVAII-acarbose complex and inactive mutant TVAII (D325N/D421N)/alpha-, beta- and gamma-CDs complexes were determined at resolutions of 2.9, 2.9, 2.8, and 3.1 A, respectively. In all complexes, the interactions between ligands and enzymes at subsites -1, -2, and -3 were almost the same, but striking differences in the catalytic site structure were found at subsites +1 and +2, where Trp(356) and Tyr(374) changed the conformation of the side chain depending on the structure and size of the ligands. Trp(356) and Tyr(374) are thought to be responsible for the multiple substrate-recognition mechanism of TVAII, providing the unique substrate specificity. In the beta-CD complex, the beta-CD maintains a regular conical structure, making it difficult for Glu(354) to protonate the O-4 atom at the hydrolyzing site as a previously proposed hydrolyzing mechanism of alpha-amylase. From the x-ray structures, it is suggested that the protonation of the O-4 atom is possibly carried out via a hydrogen atom of the inter-glucose hydrogen bond at the hydrolyzing site.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15138257}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15138257 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15138257}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Complex]] | | [[Category: Complex]] |
| [[Category: Cyclodextrin]] | | [[Category: Cyclodextrin]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 12:29:15 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 20:56:59 2008'' |
