Phage Display Technology

Protein A has long been the ligand of choice in the affinity purification of immunoglobulin G 1 (IgG 1 ) monoclonal antibodies (see Notes 1 and 2 ). However, current research efforts ( 1 – 9 ) have been focused on the discovery of small molecules (peptides or peptidomimetics) that share similar binding characteristics with protein A but are more cost effective owing to small size (for ease of synthesis) and stability (for ease of regeneration). The following methods were developed as part of a proof of principle study ( 1 ) to determine whether phage display technology could be used to identify peptides as leads in the customization of ligands for affinity chromatography (see Note 3 ) and ( 2 ) to identify a peptide or peptidomimetic for use as a protein A alternative in the affinity purification of monoclonal antibodies. In this study, the constant region (pFc’ fragments; see Note 4 ) of an IgG 1 monoclonal antibody, denoted humanized anti-Tac (HAT), was used as the target for phage display in this study. HAT is a humanized monoclonal antibody against the low-affinity p55 subunit of the interleukin-2 (IL-2) receptor. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.