Weak-Affinity Chromatography

Abstract

Classical adsorption/desorption affinity chromatography (Turkova, 1978) relies upon high-affinity interactions between an immobilized ligand and a soluble ligate to form stable (bio)molecular complexes that will withstand washing to remove soluble impurities. Disruption of such complexes often requires harsh buffer conditions that lead to loss in (bio)activity of the purified ligate. For this reason, and because of its high cost, low throughput, limited reproducibility, and lack of resolving power, affinity chromatography has remained primarily a tool of the research laboratory. As technologies have emerged for economical production of relatively large quantities of homogeneous, bioactive proteins via hybridoma and recombinant molecular genetic methods, it has become feasible to incorporate into affinity matrices high concentrations of protein ligands that recognize small-molecular-weight ligates with weak affinity (K _a = 10²−10⁴ M ⁻¹) (Ohlson et al., 1988; Zopf and Ohlson, 1990). The rapid dynamics of weak-affinity binding provide the possibility for true, high-resolution chromatography of multiple analytes on a crude matrix in nearly physiological buffers under isocratic conditions.