LAUSR

Abstract Experimental measurements indicate that the Gibbs energy change is negative for the transfer from water to liquid N-methylacetamide of all the amino acid side chains [J.Biol.Chem. 261 (1986) 7220]. The rationalization of these data is still lacking. Classic scaled particle theory calculations, assigning reliable diameters to the molecules of the two liquids, indicate that the reversible work to create molecular-sized cavities is larger in water than in N-methylacetamide. This result provides a physically reliable rationalization since the reversible work of cavity creation opposes solubility, and its magnitude is independent of solute chemical properties.