Calorimetric Studies of Hydrophobic Interactions in Aqueous Solution

Abstract

Biological macromolecules such as proteins are stabilized in a narrow distribution of conformations in aqueous solution by various solute-solute (intramolecular) and solute-solvent interactions. These interactions are usually distinguished by names such as electrostatic, dipolar, hydrogen bonding or hydrophobic. Most of what we know of the magnitudes of these interactions and their molecular interpretation has been derived from defined model systems wherein each type of interaction is studied independently. We focus our attention in this report on hydrophobic interactions which have in many ways a unique mechanism for association. For example, whereas the strength of most interactions between solute molecules are decreased by the properties of liquid water, as compared to other liquids, hydrophobic interactions are a result of these properties. Association of nonpolar molecules (as in membranes) or folding of proteins which has significant contributions from this mechanism and the resultant properties of the aggregate are of pivotal importance to living systems 1.