Department of Chemistry and Biological Sciences, University of Alabama in Huntsville, Huntsville, AL, USA.
The practical application of scanning calorimetry and spectroscopic methods to measure the stability of multimeric proteins is described. Oligomeric proteins are stabilized by both the intrinsic folding energy of the subunits as well as interactions between the subunits. Oligomerization results in a concentration dependence for multimer stability, which increases logarithmically with increasing concentration. Since the increase in stability does not plateau at high protein concentrations, the effect of concentration must be described quantitatively. Straightforward mathematical methods are provided for deriving the appropriate models for multimer unfolding, and methods are presented for analyzing equilibrium unfolding data and stability using the models.