Figure 1.
Denaturant-induced unfolding of a protein from its native state to completely unfolded state through n intermediate states.
ND, IDi and UD denote the native state, intermediate state and completely unfolded state of a protein molecule, respectively. ki indicates the thermodynamic equilibrium constant for the unfolding of the protein from one stable conformation state to the next. The symbol “” implies that the unfolding of the protein by the denaturant is only at a local thermodynamic equilibrium under a local denaturant concentration range.
Figure 2.
Interactions between the protein and denaturant molecules in the denaturant-induced unfolding of proteins.
Figure 3.
Residual activity ratios (r) of bovine heart cytochrome c exposed to different concentrations of guanidine hydrochloride or urea.
□: guanidine hydrochloride; Δ: urea. The concentration of bovine heart cytochrome c was 0.50 mg/mL, and the experimental temperature was 25°C.
Figure 4.
Plots of ln(1/r−1) vs. ln[D] for the unfolding of bovine heart cytochrome c induced by guanidine hydrochloride and urea.
◊: guanidine hydrochloride; □: urea.
Table 1.
Regression correlation coefficients (R2) and characteristic unfolding parameters k and Δm for the unfolding of bovine heart cytochrome c induced by guanidine hydrochloride and urea.
Figure 5.
Molar fractions and
of native and completely unfolded bovine heart cytochrome c exposed to different concentrations of guanidine hydrochloride (A) or urea (B).
◊: native bovine heart cytochrome c; □: completely unfolded bovine heart cytochrome c.
Figure 6.
Residual activity ratios (r) of hen egg white lysozyme exposed to different concentrations of guanidine hydrochloride or urea.
Δ: guanidine hydrochloride; ○: urea. The concentration of hen egg white lysozyme was 0.50 mg/mL, and the experimental temperature was 25°C.
Figure 7.
Plots of ln(1/r−1) vs. ln[D] (A) and ln[1/(r·k1·[D])−1] vs. ln[D] (B) for the unfolding of hen egg white lysozyme induced by guanidine hydrochloride and urea.
Δ: guanidine hydrochloride; ○: urea.
Table 2.
Regression correlation coefficients (R2) and characteristic unfolding parameters k1, k2, Δm1 and Δm2 for the unfolding of hen egg white lysozymes induced by guanidine hydrochloride and urea.
Figure 8.
Molar fractions ,
and
of native, intermediate and completely unfolded hen egg white lysozyme exposed to different concentrations of guanidine hydrochloride (A) or urea (B).
□: native egg white lysozyme; ○: intermediate egg white lysozyme; Δ: completely unfolded egg white lysozyme.
Figure 9.
Residual activity ratios (r) of bovine carbonic anhydrase b exposed to different concentrations of guanidine hydrochloride or urea.
◊: guanidine hydrochloride; □: urea. The concentration of bovine carbonic anhydrase b was 0.50 mg/mL, and the experimental temperature was 25°C.
Table 3.
Regression correlation coefficients (R2) and characteristic unfolding parameters k1, k2, k3, Δm1, Δm2 and Δm3 for the unfolding of bovine carbonic anhydrase b induced by guanidine hydrochloride.
Figure 10.
Molar fractions ,
,
and
of native, molten globule, pre-molten globule and completely unfolded bovine carbonic anhydrase b exposed to different concentrations of guanidine hydrochloride.
◊: native bovine carbonic anhydrase b; □: molten globule bovine carbonic anhydrase b; Δ: pre-molten globule bovine carbonic anhydrase b; ○: completely unfolded bovine carbonic anhydrase b.
Table 4.
Regression correlation coefficients (R2) and characteristic unfolding parameters ki and Δmi for the unfolding of proteins induced with different denaturants.
Figure 11.
Plots of lnki vs. Δmi for the unfolding of some proteins induced by denaturants.
◊: guanidine hydrochloride; □: urea; Δ: methanol.