1exp: Difference between revisions
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==Overview== | ==Overview== | ||
The three-dimensional structure of a catalytically competent | The three-dimensional structure of a catalytically competent glycosyl-enzyme intermediate of a retaining beta-1,4-glycanase has been determined at a resolution of 1.8 A by X-ray diffraction. A fluorinated slow substrate forms an alpha-D-glycopyranosyl linkage to one of the two invariant carboxylates, Glu 233, as supported in solution by 19F-NMR studies. The resulting ester linkage is coplanar with the cyclic oxygen of the proximal saccharide and is inferred to form a strong hydrogen bond with the 2-hydroxyl of that saccharide unit in natural substrates. The active-site architecture of this covalent intermediate gives insights into both the classical double-displacement catalytic mechanism and the basis for the enzyme's specificity. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Cellulomonas fimi]] | [[Category: Cellulomonas fimi]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Johns, K | [[Category: Johns, K L.]] | ||
[[Category: Rose, D | [[Category: Rose, D R.]] | ||
[[Category: Tull, D.]] | [[Category: Tull, D.]] | ||
[[Category: White, A.]] | [[Category: White, A.]] | ||
[[Category: Withers, S | [[Category: Withers, S G.]] | ||
[[Category: cellulose degradation]] | [[Category: cellulose degradation]] | ||
[[Category: glycosidase]] | [[Category: glycosidase]] | ||
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[[Category: signal]] | [[Category: signal]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:32:36 2008'' | ||
Revision as of 10:32, 21 February 2008
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BETA-1,4-GLYCANASE CEX-CD
Overview
The three-dimensional structure of a catalytically competent glycosyl-enzyme intermediate of a retaining beta-1,4-glycanase has been determined at a resolution of 1.8 A by X-ray diffraction. A fluorinated slow substrate forms an alpha-D-glycopyranosyl linkage to one of the two invariant carboxylates, Glu 233, as supported in solution by 19F-NMR studies. The resulting ester linkage is coplanar with the cyclic oxygen of the proximal saccharide and is inferred to form a strong hydrogen bond with the 2-hydroxyl of that saccharide unit in natural substrates. The active-site architecture of this covalent intermediate gives insights into both the classical double-displacement catalytic mechanism and the basis for the enzyme's specificity.
About this Structure
1EXP is a Single protein structure of sequence from Cellulomonas fimi. Known structural/functional Sites: ABC and NUC. Full crystallographic information is available from OCA.
Reference
Crystallographic observation of a covalent catalytic intermediate in a beta-glycosidase., White A, Tull D, Johns K, Withers SG, Rose DR, Nat Struct Biol. 1996 Feb;3(2):149-54. PMID:8564541
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