Thermodynamics of binding of 2-methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine to the major urinary protein

J Am Chem Soc. 2004 Feb 18;126(6):1675-81. doi: 10.1021/ja038461i.


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 (15)N and methyl side-chain (2)H 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Calorimetry
  • Crystallography, X-Ray
  • Molecular Sequence Data
  • Nitrogen Isotopes
  • Nuclear Magnetic Resonance, Biomolecular / methods
  • Protein Binding
  • Protein Conformation
  • Proteins / chemistry*
  • Proteins / metabolism*
  • Pyrazines / chemistry*
  • Pyrazines / metabolism*
  • Thermodynamics


  • Nitrogen Isotopes
  • Proteins
  • Pyrazines
  • major urinary proteins
  • 2-isobutyl-3-methoxypyrazine