1edt
From Proteopedia
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CRYSTAL STRUCTURE OF ENDO-BETA-N-ACETYLGLUCOSAMINIDASE H AT 1.9 ANGSTROMS RESOLUTION: ACTIVE SITE GEOMETRY AND SUBSTRATE RECOGNITION
Overview
BACKGROUND: Endo-beta-N-acetylglucosaminidase H (Endo H), an, endoglycosidase secreted by Streptomyces plicatus, hydrolyzes the, glycosidic bond between the core N-acetyglucosamine residues of, asparagine-linked high-mannose oligosaccharides. Endo H is a commonly used, reagent in glycobiology research, including the characterization of, oligosaccharides in glycoproteins. On-going crystallographic studies of, Endo H and related endoglycosidases are aimed at identifying the molecular, features that determine the different substrate specificities of these, enzymes. RESULTS: The three-dimensional structure of Endo H has been, determined to 1.9 A resolution. The overall fold of the enzyme is that of, an irregular (alpha/beta)8-barrel comprising eight, beta-strand/loop/alpha-helix units. Units 5 and 6 have very short loop, sections at the top of the molecule and their alpha-helices are replaced, by sections of extended geometry. The loop of unit 2 includes a small, two-stranded antiparallel beta-sheet. A shallow curved cleft runs across, the surface of the molecule from the area of units 5 and 6, over the core, of the beta-barrel to the area of the beta-sheet of loop 2. This cleft, contains the putative catalytic residues Asp130 and Glu132 above the core, of the beta-barrel. These residues are surrounded by several aromatic, residues. The loop 2 area of the cleft is formed by neutral polar, residues, mostly asparagines. CONCLUSIONS: The structure of Endo H is very, similar to that of Endo F1, a closely related endoglycosidase secreted by, Flavobacterium meningosepticum. Detailed comparison of the structures of, Endo H and Endo F1 supports the model previously proposed for substate, binding and recognition, in which the area of loop 2 determines the, substrate specificity and the alpha-helices of units 5 and 6 are missing, to accommodate the protein moiety of the substrate.
About this Structure
1EDT is a Single protein structure of sequence from Streptomyces plicatus. Active as Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase, with EC number 3.2.1.96 Full crystallographic information is available from OCA.
Reference
Crystal structure of endo-beta-N-acetylglucosaminidase H at 1.9 A resolution: active-site geometry and substrate recognition., Rao V, Guan C, Van Roey P, Structure. 1995 May 15;3(5):449-57. PMID:7663942
Page seeded by OCA on Tue Nov 20 13:55:35 2007
