Portal de Periódicos da CAPES

Thermodynamics of Protein Interactions with Urea and Guanidinium Hydrochloride

1999; American Chemical Society; Volume: 103; Issue: 23 Linguagem: Inglês

10.1021/jp990413q

1520-6106

George I. Makhatadze,

Lipid Membrane Structure and Behavior

Urea and guanidinium hydrochloride (GdmCl) are used as chemical denaturing agents in the study of protein folding and stability. It has been known for a long time that the free energy of unfolding estimated using the linear extrapolation model (LEM) for the GdmCl-induced unfolding is often higher than the corresponding values obtained using LEM for the urea-induced unfolding. It was noted by Nick Pace that "This disagreement is puzzling and deserves further studies" (Pace, C. N. Methods Enzymol. 1986, 131, 266). This paper summarizes thermodynamic information on the denaturing action of urea and GdmCl that may explain why LEM analysis of GdmCl-induced unfolding in many cases does not provide a "true" stability of the protein. The answer to the puzzle seems to be the nonapplicability of LEM for the data analysis obtained using GdmCl-induced denaturation.