1dyp
From Proteopedia
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'''1,3-ALPHA-1,4-BETA-D-GALACTOSE-4-SULFATE-3,6-ANHYDRO-D-GALACTOSE 4 GALACTOHYDROLASE''' | '''1,3-ALPHA-1,4-BETA-D-GALACTOSE-4-SULFATE-3,6-ANHYDRO-D-GALACTOSE 4 GALACTOHYDROLASE''' | ||
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[[Category: Dideberg, O.]] | [[Category: Dideberg, O.]] | ||
[[Category: Michel, G.]] | [[Category: Michel, G.]] | ||
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Kappa-carrageenan double helix degradation]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:26:35 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 11:26, 2 May 2008
1,3-ALPHA-1,4-BETA-D-GALACTOSE-4-SULFATE-3,6-ANHYDRO-D-GALACTOSE 4 GALACTOHYDROLASE
Overview
BACKGROUND: kappa-carrageenans are gel-forming, sulfated 1,3-alpha-1,4-beta-galactans from the cell walls of marine red algae. The kappa-carrageenase from the marine, gram-negative bacterium Pseudoalteromonas carrageenovora degrades kappa-carrageenan both in solution and in solid state by an endoprocessive mechanism. This beta-galactanase belongs to the clan-B of glycoside hydrolases. RESULTS: The structure of P. carrageenovora kappa-carrageenase has been solved to 1.54 A resolution by the multiwavelength anomalous diffraction (MAD) method, using a seleno-methionine-substituted form of the enzyme. The enzyme folds into a curved beta sandwich, with a tunnel-like active site cavity. Another remarkable characteristic is the presence of an arginine residue at subsite -1. CONCLUSIONS: The crystal structure of P. carrageenovora kappa-carrageenase is the first three-dimensional structure of a carrageenase. Its tunnel-shaped active site, the first to be reported for enzymes other than cellulases, suggests that such tunnels are associated with the degradation of solid polysaccharides. Clan-B glycoside hydrolases fall into two subgroups, one with catalytic machinery held by an ancestral beta bulge, and the other in which it is held by a regular beta strand. At subsite -1, all of these hydrolases exhibit an aromatic amino acid that interacts with the hexopyranose ring of the monosaccharide undergoing catalysis. In addition, in kappa-carrageenases, an arginine residue recognizes the sulfate-ester substituents of the beta-linked kappa-carrageenan monomers. It also appears that, in addition to the nucleophile and acid/base catalysts, two other amino acids are involved with the catalytic cycle, accelerating the deglycosylation step.
About this Structure
1DYP is a Single protein structure of sequence from Pseudoalteromonas carrageenovora. Full crystallographic information is available from OCA.
Reference
The kappa-carrageenase of P. carrageenovora features a tunnel-shaped active site: a novel insight in the evolution of Clan-B glycoside hydrolases., Michel G, Chantalat L, Duee E, Barbeyron T, Henrissat B, Kloareg B, Dideberg O, Structure. 2001 Jun;9(6):513-25. PMID:11435116 Page seeded by OCA on Fri May 2 14:26:35 2008
