Molar fractions , and of native, intermediate and completely unfolded hen egg white lysozyme exposed to different concentrations of guanidine hydrochloride (A) or urea (B).

<p>□: native egg white lysozyme; ○: intermediate egg white lysozyme; Δ: completely unfolded egg white lysozyme.</p

Regression correlation coefficients (<i>R</i>²) and characteristic unfolding parameters <i>k</i>₁, <i>k</i>₂, Δ<i>m</i>₁ and Δ<i>m</i>₂ for the unfolding of hen egg white lysozymes induced by guanidine hydrochloride and urea.

<p>Regression correlation coefficients (<i>R</i>²) and characteristic unfolding parameters <i>k</i>₁, <i>k</i>₂, Δ<i>m</i>₁ and Δ<i>m</i>₂ for the unfolding of hen egg white lysozymes induced by guanidine hydrochloride and urea.</p

Interactions between the protein and denaturant molecules in the denaturant-induced unfolding of proteins.

<p>Interactions between the protein and denaturant molecules in the denaturant-induced unfolding of proteins.</p

Residual activity ratios (<i>r</i>) of hen egg white lysozyme exposed to different concentrations of guanidine hydrochloride or urea.

<p>Δ: guanidine hydrochloride; ○: urea. The concentration of hen egg white lysozyme was 0.50 mg/mL, and the experimental temperature was 25°C.</p

Regression correlation coefficients (<i>R</i>²) and characteristic unfolding parameters <i>k</i>_i and Δ<i>m</i>_i for the unfolding of proteins induced with different denaturants.

<p>Regression correlation coefficients (<i>R</i>²) and characteristic unfolding parameters <i>k</i>_i and Δ<i>m</i>_i for the unfolding of proteins induced with different denaturants.</p

Residual activity ratios (<i>r</i>) of bovine heart cytochrome <i>c</i> exposed to different concentrations of guanidine hydrochloride or urea.

<p>□: guanidine hydrochloride; Δ: urea. The concentration of bovine heart cytochrome <i>c</i> was 0.50 mg/mL, and the experimental temperature was 25°C.</p

Plots of ln(1/<i>r</i>−1) vs. ln[D] (A) and ln[1/(<i>r</i>·<i>k</i>₁·[D])−1] vs. ln[D] (B) for the unfolding of hen egg white lysozyme induced by guanidine hydrochloride and urea.

<p>Δ: guanidine hydrochloride; ○: urea.</p

Plots of ln(1/<i>r</i>−1) vs. ln[D] for the unfolding of bovine heart cytochrome <i>c</i> induced by guanidine hydrochloride and urea.

<p>◊: guanidine hydrochloride; □: urea.</p

Residual activity ratios (<i>r</i>) of bovine carbonic anhydrase <i>b</i> exposed to different concentrations of guanidine hydrochloride or urea.

<p>◊: guanidine hydrochloride; □: urea. The concentration of bovine carbonic anhydrase <i>b</i> was 0.50 mg/mL, and the experimental temperature was 25°C.</p

Denaturant-induced unfolding of a protein from its native state to completely unfolded state through <i>n</i> intermediate states.

<p>N<i>_D</i>, I<i>_Di</i> and U<i>_D</i> denote the native state, intermediate state and completely unfolded state of a protein molecule, respectively. <i>k</i>_i 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.</p