Possibility for discriminating between two representative non two-state thermal unfolding models of proteins by DSC

Possible differences between two representative non two-state thermal unfol ding mechanisms of protein are discussed concerning differential scanning c alorimetry. Numerical simulations showed that, by DSC measurement, it is ha rd to discriminate between the independent model, which assumes independent unfolding domains in a protein, and the sequential model, which assumes in termediate(s) between native and denatured states, especially when values o f molecular weight, denaturation enthalpy, and difference in denaturation t emperature of each denaturation process are large. DSC curve analysis of As pergillus niger glucoamylase based on these two models gave essentially the same thermodynamic parameters.