Design and Characterization of Affinity Peptides Based On the Interactions With Human Immunoglobulin

The increase in huge demand of antibodies, the most promising biopharmaceuticals for the treatment of a number of diseases in recent years, has resulted in a need for the more efficient, less costly, more specific downstream production process to separate and purify antibodies from serum and mammalian cell culture than the current processes accounting for 50-80% of the overall production costs. In this study, a series of polypeptides were designed based on the interactions between the peptides and IgG or HSA using the molecular simulations. The binding energy between the lead peptide ligands and Fc fragment of antibody was evaluated using the AutoDock. The  adsorption behaviour between Fc fragments and lead peptide ligands in the aqueous environment was further investigated using the Gromacs. The associated constant and dissociated constant of ligand to antibody were measured using the SPR technology. The dynamic binding capacity, purity and recovery were measured when the agarose was used as media. The SPR results indicated that the interactions between the lead affinity peptides and IgG or HSA varied with pH, ionic strength and buffer. The selectivity of the lead peptides to IgG was optimized at NaCl concentration of 150 mM at pH 7.0 when HEPES was used as the buffer. These results demonstrated the potential for rational design and synthesis of affinity peptides which can be used in the downstream production processes to separate and purify antibodies with high efficient and low cost.