Immobilized metal affinity chromatography of human growth hormone. Effect of ligand density

Immobilized metal affinity chromatography was examined as a method for the purification of recombinant human growth hormone, somatotropin. Cellulose-based chelating supports, Chelat-Granocel, of a different content of ligand, charged with Cu(II), were assessed for their ability to bind the protein from both crude extract and solution purified by two chromatography steps. Human growth hormone was found to exhibit high affinity to chelating support charged with Cu(II). One step of immobilized metal affinity chromatography on Chelat-Granocel gives 80% purification of the protein. It was shown that the protein retention depends highly on the ligand density. By regulating sorbent ligand density a favourable desorption was achieved.