Protein recognition of immobilized ligands: promotion of selective adsorption

We are using simple immobilized ligands to evaluate the biochemistry and mechanisms of selective, high-affinity, protein adsorption events. Several specific means have recently been developed to more selectively utilize the favorable entropy changes associated with the displacement of protein-bound water during the formation and stabilization of protein-ligand recognition events. For protein and peptide immobilization these include, besides hydrophobic interaction, for example, metal ion, pi-electron-mediated, and thiophilic interactions. This latter type of protein-ligand recognition process represents a previously unrecognized interaction mechanism of considerable selectivity, affinity, and utility. Specific examples of the above-mentioned principles and protein fractionations include (a) thiophilic adsorption of immunoglobulins to achieve immunoglobulin-free serum for in vitro production and purification of monoclonal antibodies and (b) urea-induced binding of estrogen-receptor proteins to immobilized DNA. The interaction mechanisms are discussed in terms of the molecular architecture of protein surfaces. We present possibilities for the further utilization of these immobilized ligands and their associated proteins in the areas of clinical biochemistry and immunology.