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42748-AC4
Pressure Perturbation Calorimetry and Protein Surface Area

Gary J. Pielak, University of North Carolina (Chapel Hill)

Changes in accessible surface area influence the energetics of protein-protein interactions, protein-ligand ligand binding, and protein folding. Our worked focused on folding, specifically alpha-helix formation. The alpha-helix is an important target because it comprises approximately one third of the secondary structure of globular proteins. Investigating the change in accessible surface area upon alpha-helix formation, however, has proven to be challenging due to the difficulty in modeling the many states of an unfolded protein. We used pressure perturbation calorimetry to measure changes in solute-solvent interactions upon helix formation. Our data show that the change is small and that the surface of the helix is less hydrophobic than the surface of the coil.

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