2gz6
Crystal Structure Of Anabaena sp. CH1 N-acetyl-D-glucosamine 2-epimerase At 2.0 A
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OverviewOverview
N-Acetyl-d-glucosamine 2-epimerase (GlcNAc 2-epimerase) catalyzes the, reversible epimerization between N-acetyl-d-glucosamine (GlcNAc) and, N-acetyl-d-mannosamine (ManNAc). We report here the 2.0 A resolution, crystal structure of the GlcNAc 2-epimerase from Anabaena sp. CH1. The, structure demonstrates an (alpha/alpha)(6) barrel fold, which shows, structural homology with porcine GlcNAc 2-epimerase as well as a number of, glycoside hydrolase enzymes and other sugar-metabolizing enzymes. One side, of the barrel structure consists of short loops involved in dimer, interactions. The other side of the barrel structure is comprised of long, loops containing six short beta-sheets, which enclose a putative central, active-site pocket. Site-directed mutagenesis of conserved residues near, the N-terminal region of the inner alpha helices shows that R57, H239, E308, and H372 are strictly required for activity. E242 and R375 are also, essential in catalysis. Based on the structure and kinetic analysis, H239, and H372 may serve as the key active site acid/base catalysts. These, results suggest that the (alpha/alpha)(6) barrel represents a steady fold, for presenting active-site residues in a cleft at the N-terminal ends of, the inner alpha helices, thus forming a fine-tuned catalytic site in, GlcNAc 2-epimerase.
About this StructureAbout this Structure
2GZ6 is a Protein complex structure of sequences from Anabaena sp.. Active as Mannose-6-phosphate isomerase, with EC number 5.3.1.8 Full crystallographic information is available from OCA.
ReferenceReference
The Central Cavity from the (Alpha/Alpha)(6) Barrel Structure of Anabaena sp. CH1 N-Acetyl-d-glucosamine 2-Epimerase Contains Two Key Histidine Residues for Reversible Conversion., Lee YC, Wu HM, Chang YN, Wang WC, Hsu WH, J Mol Biol. 2007 Mar 30;367(3):895-908. Epub 2006 Nov 6. PMID:17292397
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