Ligand Density and Resin Surface Design
Previous studies demonstrated a strong correlation between
chromatographic ligand docking binding affinities (surrogate for ΔG) and
chromatographic separation (k’) (Insaidoo et al., 2015). While these
results may hold true for a smaller biological molecule, the complexity
of possible ligand interaction sites on an antibody makes such an
approach challenging (Hanke & Ottens, 2014). To address the complexity
in chromatographic separation, a molecular model of agarose ligand
complex was formulated to capture a broader range of ligand densities
and interaction sites. The ligands were attached to the resin surface
with a separation distance of 10-14 Å, ranging from one attached ligand
to six ligands per resin area. From our internal calculation, these
agarose models span the range of low to medium and high-density resin
that is commercially available (Figure 2A).