Statistical thermodynamic analysis of differential scanning calorimetry data: Structural deconvolution of heat capacity function of proteins

The thermodynamic information obtained calorimetrically can be linked directly to the structure of a protein in a quantitative fashion. This development has opened the doors to a direct structural deconvolution of the heat capacity function. The structural thermodynamic approach has permitted the development of an accurate structural parametrization of protein energetics and the possibility of evaluating the folding/unfolding partition function from the crystallographic or nuclear magnetic resonance (NMR) solution structure of a protein. This chapter discusses the linkage between the thermodynamics and structure through the partition function. The most fundamental quantity required to account for the stability and folding behavior of monomeric proteins is the partition function, Q, defined as the sum of the statistical weights of all the states accessible to a protein. Evaluation of the partition function requires the identification and enumeration of the relevant folding states of the protein and their Gibbs free energies. The development of a structural parametrization of the protein folding energetics has set the basis for the development of algorithms aimed at evaluating the partition function from the crystallographic or NMR solution structure of a protein.