Enthalpic Contribution to Protein Stability: Insights from Atom-Based Calculations and Statistical Mechanics

Abstract

This chapter discusses published analyses of protein stability based on model compound data and outlines the assumptions that have been made. The enthalpy of protein folding is considered and a thermodynamic cycle is used to relate the measurements to quantities that can be calculated. The focus is on the enthalpy of denaturation because it is most directly accessible to calculations. The experiments and analysis of Privalov and co-workers, particularly which of Makhatadze and Privalov are considered in detail because these measurements provide the most complete results on the thermodynamics of proteins. The estimates of internal van der Waals and hydrogen bonding contributions to the enthalpy difference between the native and denatured states of the protein are compared with the calculations of the van der Waals and electrostatic terms (the latter includes hydrogen bonding) from an atom-based model. Statistical mechanical calculations and molecular dynamics simulations are used to estimate the difference in solvation enthalpy, as well as the free energy, of the native and unfolded states. © 1995, Academic Press Inc.