(499f) Computational Design of Peptide Ligands for the Bioseparation of “Fab” Antibody Fragments

An exciting alternative therapeutic to monoclonal antibodies are antigen-binding fragments of antibodies, “Fab”, which retain the target specificity of their parental MAb but are easier and cheaper to produce, and have higher tissue penetration and quicker uptake. A key issue in Fab production is separating it from the cell cultures in which it is made during bio manufacturing. The industry standard to capture Fab from cell culture fluid is affinity chromatography using the affinity ligand Protein L which itself has a number of drawbacks including very high cost, low chemical stability, modest binding capacity, and potential immunogenicity. We describe a novel computational approach to discover new short peptides that can bind Fab specifically and selectively and then release it in eluting conditions in affinity chromatography columns thereby avoiding the need for harsh acidic conditions that denature antibodies. Two of the designed binders from the computational algorithm, were synthesized on Toyopearl Amino 650 M resin , tested for binding and purification of IgG from a cell culture harvest, and found to bind strongly and selectively .