1dex
From Proteopedia
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RHAMNOGALACTURONAN ACETYLESTERASE FROM ASPERGILLUS ACULEATUS AT 1.9 A RESOLUTION
Overview
BACKGROUND: The complex polysaccharide rhamnogalacturonan constitutes a, major part of the hairy region of pectin. It can have different types of, carbohydrate sidechains attached to the rhamnose residues in the backbone, of alternating rhamnose and galacturonic acid residues; the galacturonic, acid residues can be methylated or acetylated. Aspergillus aculeatus, produces enzymes that are able to perform a synergistic degradation of, rhamnogalacturonan. The deacetylation of the backbone by, rhamnogalacturonan acetylesterase (RGAE) is an essential prerequisite for, the subsequent action of the enzymes that cleave the glycosidic bonds., RESULTS: The structure of RGAE has been determined at 1.55 A resolution., RGAE folds into an alpha/beta/alpha structure. The active site of RGAE is, an open cleft containing a serine-histidine-aspartic acid catalytic triad., The position of the three residues relative to the central parallel beta, sheet and the lack of the nucleophilic elbow motif found in structures, possessing the alpha/beta hydrolase fold show that RGAE does not belong to, the alpha/beta hydrolase family. CONCLUSIONS: Structural and sequence, comparisons have revealed that, despite very low sequence similarities, RGAE is related to seven other proteins. They are all members of a new, hydrolase family, the SGNH-hydrolase family, which includes the, carbohydrate esterase family 12 as a distinct subfamily. The, SGNH-hydrolase family is characterised by having four conserved blocks of, residues, each with one completely conserved residue; serine, glycine, asparagine and histidine, respectively. Each of the four residues plays a, role in the catalytic function.
About this Structure
1DEX is a Single protein structure of sequence from Aspergillus aculeatus with NAG as ligand. Full crystallographic information is available from OCA.
Reference
Rhamnogalacturonan acetylesterase elucidates the structure and function of a new family of hydrolases., Molgaard A, Kauppinen S, Larsen S, Structure. 2000 Apr 15;8(4):373-83. PMID:10801485
Page seeded by OCA on Tue Nov 20 13:13:47 2007
