Chemistry and preparation of affinity ligands useful in immunoglobulin isolation and serum protein separation

A number of synthetic affinity gels having high affinity for immunoglobulins and albumin have been prepared by first reacting hydroxyl groups of a polymer with pentafluoropyridine and 4-dimethylaminopyridine in an anhydrous polar organic solvent and then reacting the gel further with nucleophiles such as ethyleneglycol or glycine in basic aqueous solutions. Immunoglobulins can be adsorbed to the gel in either high-salt or low-salt buffers, while albumin can only be adsorbed under low-salt conditions. The identity of the eluted proteins was analyzed by gradient polyacrylamide gel electrophoresis and enzyme-linked immunosorbent assay techniques. Human, goat, mouse and rabbit serum proteins were fractionated on these gels by using different adsorption and desorption conditions. The possible structures of the ligand are discussed. The results showed that the chromatographic behavior of these new gels with synthetic, low-molecular-weight ligands was remarkably similar to that of the more complex immunoglobulin binding gel such as immobilized Protein A or Protein G.