Denaturant m values and heat capacity changes: relation to changes in accessible surface areas of protein unfolding.
Denaturant m values, the dependence of the free energy of unfolding on denaturant concentration, have been collected for a large set of proteins. The m value correlates very strongly with the amount of protein surface exposed to solvent upon unfolding, with linear correlation coefficients of R = 0.84 for urea and R = 0.87 for guanidine hydrochloride. These correlations improve to R = 0.90 when the effect of disulfide bonds on the accessible area of the unfolded protein is included. A similar dependence on accessible surface area has been found previously for the heat capacity change (delta Cp), which is confirmed here for our set of proteins. Denaturant m values and heat capacity changes also correlate well with each other. For proteins that undergo a simple two-state unfolding mechanism, the amount of surface exposed to solvent upon unfolding is a main structural determinant for both m values and delta Cp.
Myers
J K
JK
Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843, USA.
Pace
C N
CN
Scholtz
J M
JM
D000818:Animals; D002151:Calorimetry; D004798:Enzymes / Q000737:chemistry*; D019791:Guanidine; D006146:Guanidines; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008433:Mathematics; D009113:Muramidase / Q000737:chemistry; D011489:Protein Denaturation; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D012044:Regression Analysis; D006163:Ribonuclease T1 / Q000737:chemistry; D012260:Ribonucleases / Q000737:chemistry; D013816:Thermodynamics
D004798:Enzymes; D006146:Guanidines; D011506:Proteins; D012260:Ribonucleases; D006163:Ribonuclease T1; D009113:Muramidase; D019791:Guanidine