Apparent thermodynamic parameters associated with urea-induced unfolding transitions of recHuPrPC and recRaPrPC at 25°C.

The buffer contained 20 mM NaOAc, pH 5.5. ΔGH2ON→U is designated as the apparent free energy of unfolding extrapolated to zero concentration of denaturant, mN→U is the cooperativity of the unfolding transition, and Cm is the concentration of urea required to denature 50% of the protein. The CD spectrum was an average of three consecutive scans. Each experiment was repeated in triplicate for each sample.