Biophysical characterisation of GlycoPEGylated recombinant human factor VIIa

The effects of GlycoPEGylation on the structural, kinetic and thermal stability of recombinant human FVIIa were investigated using rFVIIa and linear 10 kDa and branched 40 kDa GlycoPEGylated(®) recombinant human FVIIa derivatives. The secondary and tertiary structure of rFVIIa measured by circular dichroism (CD) was maintained upon PEGylation. In contrast, the thermal and kinetic stability of rFVIIa was affected by GlycoPEGylation, as the apparent unfolding temperature T(m) measured by differential scanning calorimetry (DSC) and the temperature of aggregation, T(agg), measured by light scattering (LS) both increased with GlycoPEGylation. Both T(m) and T(agg) were independent of the molecular weight and the shape of the PEG chain. From the present biophysical characterisation it is concluded that after GlycoPEGylation, rFVIIa appears to be unaffected structurally (secondary and tertiary structure), slightly stabilised thermally (unfolding temperature) and stabilised kinetically (temperature of aggregation).