Effect of posttranslational modifications on the thermal stability of a recombinant monoclonal antibody

The effect of oligosaccharides and C-terminal lysine residues on the thermal stability of a recombinant IgG1 monoclonal antibody was investigated using differential scanning calorimetry (DSC). The C-terminal lysine did not appear to affect the thermal stability of this IgG1 molecule. However, oligosaccharides, which are buried between the two CH2 domains, provided significant stabilizing energy. Characterization of the Fab and Fc after papain digestion suggested that the stabilizing effect of oligosaccharides on this molecule was through stabilizing CH2 domains. Oligosaccharides had little effect on the thermal stability of Fab region and CH3 domains. It was also interesting to note that both intact IgG1 antibody and its Fab, but not the Fc regions, appeared to form precipitate after thermal unfolding under the experimental conditions.