Fig. 1.
Sialylation destabilizes the Cγ2 domain of IgG1 Fc. (A) Circular dichroism spectra of IgG1 Fc glycoforms recorded in the far UV range (190–260 nm). Spectra represent an average of four scans with buffer spectra subtracted from sample spectra. (B) Thermal denaturation spectra of Fc glycoforms measured at 206.5 nm. (C) Change in free energy of unfolding, ΔGU, with increasing concentration of chemical denaturant (GnHCl) calculated by the linear extrapolation method. Y-intercept estimates ΔGH2O in aqueous solvent; m value (slope) correlates to solvent-accessible surface area exposed upon unfolding. (D) Fluorescence spectra of sFc and NAse Fc bound to hydrophobic probe ANS.