The problem of the stability globular proteins.

The article gives a survey on protein stability. Starting out from approaches for stability measurement which are based on the determination of Gibbs energy change in protein unfolding by denaturants, protonation, heat, scanning calorimetry, and hydrogen exchange, their implications such as reversibility, completeness of unfolding and the two-state assumption are dealt with. A data compilation of Gibbs energy change in unfolding of different proteins is given. The data, which for the most part range between 25 and 60 kJ mol-1 are discussed in terms of protein functioning, turnover, and structural properties. Phase diagrams are proposed in order to realize a more comprehensive thermodynamic treatment of proteins. Factors which contribute to protein stability are summarized. The paper includes the thermodynamic principles of protein stability as well as special studies on proteolytic fragments, amino acid replacements, cross links, prosthetic groups, and ions which contribute to protein stability.