Planck-Benzinger thermal work function: thermodynamic characterization of the carboxy-terminus of p53 peptide fragments.

The thermodynamic parameters for six p53 carboxy-terminus peptide fragments as determined by analytical ultracentrifugal analysis were compared over the experimental temperature range of 275-310 K to evaluate the Gibbs free energy change as a function of temperature, ΔG°(T), from 0 to 400 K using our general linear third-order fitting function, ΔG°(T) = α + βT² + γT³. Data obtained at the typical experimental temperature range are not sufficient to accurately describe the variations observed in the oligomerization of these p53 fragments. It is necessary to determine a number of thermodynamic parameters, all of which can be precisely assessed using this general third-order linear fitting function. These are the heat of reaction, innate temperature-invariant enthalpy, compensatory temperatures and the thermodynamic molecular switch occurring at the thermal set point. This methodology can be used to distinguish the characteristic structure and stability of p53 carboxy-terminal fragments or other p53 mutants. It should be used for the thermodynamic characterization of any interacting biological system.