6533b86dfe1ef96bd12c9515

RESEARCH PRODUCT

Entropy–enthalpy compensation at the single protein level: pH sensing in the bacterial channel OmpF

María Queralt-martínSalvador MafeVicente M. AguilellaAntonio AlcarazCarmina Verdiá-báguena

subject

Models Molecularentropy-enthalpy compensationChemistryLigandEntropyEnthalpyBinding energyElectric ConductivitypH sensingPorinsConductanceThermodynamicsHydrogen-Ion ConcentrationThermal conductionbinding energyPotassium ChlorideSolventModels ChemicalComputer SimulationGeneral Materials Sciencesense organsBinding siteskin and connective tissue diseasesentropyEntropy (order and disorder)

description

The pH sensing mechanism of the OmpF channel operates via ligand modification: increasing acidity induces the replacement of cations with protons in critical binding sites decreasing the channel conductance. Aside from the change in enthalpy associated with the binding, there is also a change in the microscopic arrangements of ligands, receptors and the surrounding solvent. We show that the pH-modulation of the single channel conduction involves small free energy changes because large enthalpic and entropic contributions change in opposite ways, demonstrating an approximate enthalpy–entropy compensation for different salts and concentrations. We wish to acknowledge the support from the Spanish Ministry of Economy and Competitiveness (MINECO Projects FIS2013-40473-P and MAT2012-32084), Generalitat Valenciana (Prometeo 2012/069), FEDER and Fundació Caixa Castelló-Bancaixa (Project No. P1-1B2012-03).

yearjournalcountryeditionlanguage
2014-11-07
10.1039/c4nr03811h