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| {{STRUCTURE_2d5j| PDB=2d5j | SCENE= }} | | {{STRUCTURE_2d5j| PDB=2d5j | SCENE= }} |
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| '''Unsaturated Glucuronyl Hydrolase Triggers Hydration of Vinyl Ether Group but not of Glycosidic Bond'''
| | ===Unsaturated Glucuronyl Hydrolase Triggers Hydration of Vinyl Ether Group but not of Glycosidic Bond=== |
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| ==Overview==
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| Unsaturated glucuronyl hydrolase (UGL), which is a member of glycoside hydrolase family GH-88, is a bacterial enzyme that degrades mammalian glycosaminoglycans and bacterial biofilms. The enzyme, which acts on unsaturated oligosaccharides with an alpha-glycoside bond produced by microbial polysaccharide lyases responsible for bacterial invasion of host cells, was believed to release 4-deoxy-l-threo-5-hexosulose-uronate (unsaturated glucuronic acid, or DeltaGlcA) and saccharide with a new nonreducing terminus by hydrolyzing the glycosidic bond. We detail the crystal structures of wild-type inactive mutant UGL of Bacillus sp. GL1 and its complex with a substrate (unsaturated chondroitin disaccharide), identify active site residues, and postulate a reaction mechanism catalyzed by UGL that triggers the hydration of the vinyl ether group in DeltaGlcA, based on the structural analysis of the enzyme-substrate complex and biochemical analysis. The proposed catalytic mechanism of UGL is a novel case among known glycosidases. Under the proposed mechanism, Asp-149 acts as a general acid and base catalyst to protonate the DeltaGlcA C4 atom and to deprotonate the water molecule. The deprotonated water molecule attacks the DeltaGlcA C5 atom to yield unstable hemiketal; this is followed by spontaneous conversion to an aldehyde (4-deoxy-l-threo-5-hexosulose-uronate) and saccharide through hemiacetal formation and cleavage of the glycosidic bond. UGL is the first clarified alpha(6)/alpha(6)-barrel enzyme using aspartic acid as the general acid/base catalyst.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16893885}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16893885 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16893885}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Alpha/alpha barrel]] | | [[Category: Alpha/alpha barrel]] |
| [[Category: Unsaturated glucuronyl hydrolase]] | | [[Category: Unsaturated glucuronyl hydrolase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 23:44:50 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 02:28:53 2008'' |
