1yp7
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Van der Waals Interactions Dominate Hydrophobic Association in a Protein Binding Site Occluded From Solvent Water
OverviewOverview
In the present study we examine the enthalpy of binding of, 2-methoxy-3-isobutylpyrazine (IBMP) to the mouse major urinary protein, (MUP), using a combination of isothermal titration calorimetry (ITC), NMR, X-ray crystallography, all-atom molecular dynamics simulations, and, site-directed mutagenesis. Global thermodynamics data derived from ITC, indicate that binding is driven by favorable enthalpic contributions, rather than a classical entropy-driven signature that might be expected, given that the binding pocket of MUP-1 is very hydrophobic. The only, ligand-protein hydrogen bond is formed between the side-chain hydroxyl of, Tyr120 and the ring nitrogen of the ligand in the wild-type protein. ITC, measurements on the binding of IBMP to the Y120F mutant demonstrate a, reduced enthalpy of binding, but nonetheless binding is still enthalpy, dominated. A combination of solvent isotopic substitution ITC measurements, and all-atom molecular dynamics simulations with explicit inclusion of, solvent water suggests that solvation is not a major contributor to the, overall binding enthalpy. Moreover, hydrogen/deuterium exchange, measurements suggest that there is no significant contribution to the, enthalpy of binding derived from "tightening" of the protein structure., Data are consistent with binding thermodynamics dominated by favorable, dispersion interactions, arising from the inequality of solvent-solute, dispersion interactions before complexation versus solute-solute, dispersion interactions after complexation, by virtue of poor solvation of, the binding pocket.
About this StructureAbout this Structure
1YP7 is a Single protein structure of sequence from Mus musculus with CD as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Van der Waals interactions dominate ligand-protein association in a protein binding site occluded from solvent water., Barratt E, Bingham RJ, Warner DJ, Laughton CA, Phillips SE, Homans SW, J Am Chem Soc. 2005 Aug 24;127(33):11827-34. PMID:16104761
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