Solvation of proteins: Linking thermodynamics to geometry

We calculate the solvation free energy of proteins in the tube model of Banavar and Maritan [Rev. Mod. Phys. 75, 23 (2003)] using morphological thermodynamics which is based on Hadwiger's theorem of integral geometry. Thereby we extend recent results by Snir and Kamien [Science 307, 1067 (2005)] to hard-sphere solvents at finite packing fractions and obtain new conclusions. Depending on the solvent properties, parameter regions are identified where the beta sheet, the optimal helix, or neither is favored.