1djr
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(New page: 200px<br /><applet load="1djr" size="450" color="white" frame="true" align="right" spinBox="true" caption="1djr, resolution 1.30Å" /> '''HEAT-LABILE ENTEROTO...)
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Revision as of 11:13, 20 November 2007
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HEAT-LABILE ENTEROTOXIN B-PENTAMER COMPLEXED WITH M-CARBOXYPHENYL-ALPHA-D-GALACTOSE
Overview
In the quest to develop drugs against traveller's diarrhoea and cholera, the structure of the B pentamer of heat-labile enterotoxin (LT) complexed, with a new receptor-binding antagonist, m-carboxyphenyl-alpha-D-galactopyranoside, has been determined. The high, resolution obtained for this structure allowed anisotropic refinement of, the model. It was also now possible to confirm at a near-atomic resolution, the structural similarity between the B subunits of LT and the closely, related cholera toxin (CT), including the similarity in deviations of, planarity of the same peptide unit in LT and CT. The structure of the LT, complex clearly revealed different conformations for the m--carboxyphenyl, moiety of the ligand in the five B subunits of LT, while the binding modes, of the well defined galactopyranoside moieties were identical. In two, binding sites the m-carboxyphenyl moiety displayed no significant electron, density, demonstrating significant flexibility of this moiety. In a third, binding site the m-carboxyphenyl moiety could be modelled unambiguously, into the density. The two remaining binding sites were involved in crystal, packing contacts and the density for the ligands in these two binding, sites clearly revealed different binding modes, of which one conformation, was identical to and one completely different from the conformation of, m-carboxyphenyl-galactopyranoside in the third subunit. The multiple, binding modes observed in the crystal may represent the ensemble of, conformations of m-carboxyphenyl-alpha-D-galactopyranoside complexed to LT, in solution.
About this Structure
1DJR is a Single protein structure of sequence from Escherichia coli with GLA, BEZ and GOL as ligands. Full crystallographic information is available from OCA.
Reference
Structure of m-carboxyphenyl-alpha-D-galactopyranoside complexed to heat-labile enterotoxin at 1.3 A resolution: surprising variations in ligand-binding modes., Minke WE, Pickens J, Merritt EA, Fan E, Verlinde CL, Hol WG, Acta Crystallogr D Biol Crystallogr. 2000 Jul;56(Pt 7):795-804. PMID:10930826
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