A Direct Measure of the Contribution of Solvent Reorganization to the Enthalpy of Binding

Published

Journal Article

The thermodynamics of association of several binding systems, including protein—carbohydrate, small molecule—small molecule, protein—peptide, and protein—nucleic acid, were evaluated calorimetrically in light and heavy water. In every case, the enthalpy of binding in D2O was decreased relative to that in H2O: the differences range from 400 to 1800 cal mol-1. A compensating change in AS left the free energy of binding virtually unchanged in each case. A strong correlation between the differential enthalpy of binding and ACp for binding was observed, with a slope of 5 K. An analysis of the observed effect utilizing a Born-Haber thermodynamic cycle shows that the measured decrease in enthalpy represents approximately 10% of the binding enthalpy arising from solvent reorganization. For the range of systems investigated, solvent reorganization provides 25—100% of the observed enthalpy of binding. The thermodynamics of association of several binding systems, including protein—carbohydrate, small molecule—small molecule, protein—peptide, and protein—nucleic acid, were evaluated calorimetrically in light and heavy water. In every case, the enthalpy of binding in D2O was decreased relative to that in H2O: the differences range from 400 to 1800 cal mol-1. A compensating change in ΔS left the free energy of binding virtually unchanged in each case. A strong correlation between the differential enthalpy of binding and ACp for binding was observed, with a slope of 5 K. An analysis of the observed effect utilizing a Born-Haber thermodynamic cycle shows that the measured decrease in enthalpy represents approximately 10% of the binding enthalpy arising from solvent reorganization. For the range of systems investigated, solvent reorganization provides 25—100% of the observed enthalpy of binding. © 1994, American Chemical Society. All rights reserved.

Full Text

Duke Authors

Cited Authors

  • Chervenak, MC; Toone, EJ

Published Date

  • November 1, 1994

Published In

Volume / Issue

  • 116 / 23

Start / End Page

  • 10533 - 10539

Electronic International Standard Serial Number (EISSN)

  • 1520-5126

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/ja00102a021

Citation Source

  • Scopus