1hew
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(New page: 200px<br /><applet load="1hew" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hew, resolution 1.75Å" /> '''REFINEMENT OF AN ENZ...)
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Revision as of 14:26, 20 November 2007
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REFINEMENT OF AN ENZYME COMPLEX WITH INHIBITOR BOUND AT PARTIAL OCCUPANCY. HEN EGG-WHITE LYSOZYME AND TRI-N-ACETYLCHITOTRIOSE AT 1.75 ANGSTROMS RESOLUTION
Overview
The structure of the tri-N-acetylchitotriose inhibitor complex of hen, egg-white lysozyme has been refined at 1.75 A resolution, using data, collected from a complex crystal with ligand bound at less than full, occupancy. To determine the exact value of the inhibitor occupancy, a, model comprising unliganded and sugar-bound protein molecules was, generated and refined against the 1.75 A data, using a modified version of, the Hendrickson & Konnert least-squares procedure. The crystallographic, R-factor for the model was found to fall to a minimum at 55% bound sugar., Conventional refinement assuming unit occupancy was found to yield, incorrect thermal and positional parameters. Application of the same, refinement procedures to an earlier 2.0 A data set, collected, independently on different complex crystals by Blake et al. gave less, consistent results than the 1.75 A refinement. From an analysis of the, high resolution structure a detailed picture of the protein-carbohydrate, interactions in the non-productive complex has emerged, together with the, conformation and mobility changes that accompany ligand binding. The, specificity of interaction between the protein and inhibitor, bound in, subsites A to C of the active site, is seen to be generated primarily by, an extensive network of hydrogen bonds, both to the protein itself and to, bound solvent molecules. The latter also play an important role in, maintaining the structural integrity of the active site cleft in the, apo-protein.
About this Structure
1HEW is a Single protein structure of sequence from [1]. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Refinement of an enzyme complex with inhibitor bound at partial occupancy. Hen egg-white lysozyme and tri-N-acetylchitotriose at 1.75 A resolution., Cheetham JC, Artymiuk PJ, Phillips DC, J Mol Biol. 1992 Apr 5;224(3):613-28. PMID:1569548
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