1hf6
From Proteopedia
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ENDOGLUCANASE CEL5A FROM BACILLUS AGARADHAERENS IN THE ORTHORHOMBIC CRYSTAL FORM IN COMPLEX WITH CELLOTRIOSE
Overview
Non-covalent interactions between protein and ligand at the active centre, of glycosidases play an enormous role in catalysis. Dissection of these, hydrogen-bonding networks is not merely important for an understanding of, enzymatic catalysis, but is also increasingly relevant for the design of, transition-state mimics, whose tautomeric state, hydrogen-bonding, interactions and protonation contribute to tight binding. Here, atomic, resolution ( approximately 1 A) analysis of a series of complexes of the, 34 kDa catalytic core domain of the Bacillus agaradhaerens endoglucanase, Cel5A is presented. Cel5A is a 'retaining' endoglucanase which performs, catalysis via the formation and subsequent breakdown of a covalent, glycosyl-enzyme intermediate via oxocarbenium-ion-like transition states., Previous medium-resolution analyses of a series of enzymatic snapshots has, revealed conformational changes in the substrate along the reaction, coordinate (Davies et al., 1998). Here, atomic resolution analyses of the, series of complexes along the pathway are presented, including the, 'Michaelis' complex of the unhydrolysed substrate, the covalent, glycosyl-enzyme intermediate and the complex with the reaction product, cellotriose. These structures reveal intimate details of the, protein-ligand interactions, including most of the carbohydrate-associated, H atoms and the tautomeric state of crucial active-centre groups in the pH, 5 orthorhombic crystal form and serve to illustrate the potential for, atomic resolution analyses to inform strategies for enzyme inhibition.
About this Structure
1HF6 is a Single protein structure of sequence from Bacillus agaradhaerens with SO4, CT3, ACY and GOL as ligands. Active as Cellulase, with EC number 3.2.1.4 Structure known Active Site: ACI. Full crystallographic information is available from OCA.
Reference
Direct experimental observation of the hydrogen-bonding network of a glycosidase along its reaction coordinate revealed by atomic resolution analyses of endoglucanase Cel5A., Varrot A, Davies GJ, Acta Crystallogr D Biol Crystallogr. 2003 Mar;59(Pt 3):447-52. Epub 2003, Feb 21. PMID:12595701
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