Thermodynamics of Binding of 2-Methoxy-3-isopropylpyrazine and 2-Methoxy-3-isobutylpyrazine to the Major Urinary Protein

Richard J. Bingham, John B C Findlay, Shih Yang Hsieh, Arnout P. Kalverda, Alexandra Kjellberg, Chiara Perazzolo, Simon E V Phillips, Kothandaraman Seshadri, Chi H. Trinh, W. Bruce Turnbull, Geoffrey Bodenhausen, Steve W. Homans

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In the present study we examine the thermodynamics of binding of two related pyrazine-derived ligands to the major urinary protein, MUP-I, using a combination of isothermal titration calorimetry (ITC), X-ray crystallography, and NMR backbone 15N and methyl side-chain 2H relaxation measurements. Global thermodynamics data derived from ITC indicate that binding is driven by favorable enthalpic contributions, rather than the classical entropy-driven hydrophobic effect. Unfavorable entropic contributions from the protein backbone and side-chain residues in the vicinity of the binding pocket are partially offset by favorable entropic contributions at adjacent positions, suggesting a "conformational relay" mechanism whereby increased rigidity of residues on ligand binding are accompanied by increased conformational freedom of side chains in adjacent positions. The principal driving force governing ligand affinity and specificity can be attributed to solvent-driven enthalpic effects from desolvation of the protein binding pocket.

Original languageEnglish
Pages (from-to)1675-1681
Number of pages7
JournalJournal of the American Chemical Society
Issue number6
Early online date21 Jan 2004
Publication statusPublished - 18 Feb 2004
Externally publishedYes


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