1kjl
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High Resolution X-Ray Structure of Human Galectin-3 in complex with LacNAc
OverviewOverview
The high-resolution X-ray crystal structures of the carbohydrate, recognition domain of human galectin-3 were solved in complex with, N-acetyllactosamine (LacNAc) and the high-affinity inhibitor, methyl, 2-acetamido-2-deoxy-4-O-(3-deoxy-3-[4-methoxy-2,3,5,6-tetrafluorobenzamido, ]-beta-D-galactopyranose)-beta-D-glucopyranoside, to gain insight into the, basis for the affinity-enhancing effect of the, 4-methoxy-2,3,5,6-tetrafluorobenzamido moiety. The structures show that, the side chain of Arg144 stacks against the aromatic moiety of the, inhibitor, an interaction made possible by a reorientation of the side, chain relative to that seen in the LacNAc complex. Based on these, structures, synthesis of second generation LacNAc derivatives carrying, aromatic amides at 3'-C, followed by screening with a novel fluorescence, polarization assay, has led to the identification of inhibitors with, further enhanced affinity for galectin-3 (K(d) > or = 320 nM). The, thermodynamic parameters describing the binding of the galectin-3, C-terminal to selected inhibitors were determined by isothermal titration, calorimetry and showed that the affinity enhancements were due to, favorable enthalpic contributions. These enhancements could be, rationalized by the combined effects of the inhibitor aromatic structure, on a cation-Pi interaction and of direct interactions between the aromatic, substituents and the protein. The results demonstrate that protein-ligand, interactions can be significantly enhanced by the fine-tuning of, arginine-arene interactions.
About this StructureAbout this Structure
1KJL is a Single protein structure of sequence from Homo sapiens with CL and BR as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structural and thermodynamic studies on cation-Pi interactions in lectin-ligand complexes: high-affinity galectin-3 inhibitors through fine-tuning of an arginine-arene interaction., Sorme P, Arnoux P, Kahl-Knutsson B, Leffler H, Rini JM, Nilsson UJ, J Am Chem Soc. 2005 Feb 16;127(6):1737-43. PMID:15701008
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