Affinity chromatography is the method of choice for biomolecule separation and isolation with highly specific target recognition; it is ideally suited to the purification of immunotherapeutic proteins (i.e., mAbs). Conventional affinity purification protocols are based on natural immunoglobulin (Ig)-binding proteins, which are expensive to produce, labile, unstable, and exhibit lot-to-lot variability. Biological ligands are now being replaced by cost-effective, synthetic ligands, derived from the concepts of rational design and combinatorial chemistry, aided by in silico approaches. In this chapter, we describe a new synthetic procedure for the development of affinity ligands for immunoglobulins based on the multicomponent Ugi reaction. The lead ligand developed herein is specific for the IgG-Fab fragment and mimics Protein L (PpL), an IgG-binding protein isolated from Peptostreptococcus magnus strains and usually used for the purification of antibodies and their fragments.
