1dyp
From Proteopedia
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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 with CD and CL as ligands. Active as Kappa-carrageenase, with EC number 3.2.1.83 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 Tue Nov 20 13:41:14 2007
