title: Enthalpic and Entropic Contributions to Hydrophobicity.
abstract: Hydrophobic hydration plays a key role in a vast variety of biological processes, ranging from the formation of cells to protein folding and ligand binding. Hydrophobicity scales simplify the complex process of hydration by assigning a value describing the averaged hydrophobic character to each amino acid. Previously published scales were not able to calculate the enthalpic and entropic contributions to the hydrophobicity directly. We present a new method, based on Molecular Dynamics simulations and Grid Inhomogeneous Solvation Theory, that calculates hydrophobicity from enthalpic and entropic contributions. Instead of deriving these quantities from the temperature dependence of the free energy of hydration or as residual of the free energy and the enthalpy, we directly obtain these values from the phase space occupied by water molecules. Additionally, our method is able to identify regions with specific enthalpic and entropic properties, allowing to identify so-called "unhappy water" molecules, which are characterized by weak enthalpic interactions and unfavorable entropic constraints.
authors.affiliation: Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Tyrol, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Schauperl
authors.affiliation: Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Tyrol, Austria.
authors.forename: Maren
authors.initials: M
authors.lastname: Podewitz
authors.affiliation: Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Tyrol, Austria.
authors.forename: Birgit J
authors.initials: BJ
authors.lastname: Waldner
authors.affiliation: Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Tyrol, Austria.
authors.forename: Klaus R
authors.initials: KR
authors.lastname: Liedl
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D019277:Entropy; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D014867:Water / Q000737:chemistry
chemical_list: D000596:Amino Acids; D014867:Water