STUDY OF CONFORMATIONAL EFFECTS OF RECOMBINANT INTERFERON-GAMMA ADSORBED ON A NONPOROUS REVERSED-PHASE SILICA SUPPORT

Reversed-phase chromatography is a powerful method for separating reco mbinant interferon gamma and one of its analogues differing only by a single amino acid residue. Structural differences of the proteins expl ain this separation ability as demonstrated from adsorption studies on a non-porous reversed-phase support. To reveal the structural differe nces occurring in the adsorbed state, two different and independent me thods were employed. The variation of the retention with the slope of the linear gradient gave information about the molecular contact area of the protein with the support. For different experimental conditions , these data were correlated with the adsorbent capacities measured on an n-octadecyl-modified non-porous silica support. These supports are useful for these types of experiments because the protein is adsorbed exclusively at the external surface of the beads. Moreover, a small a mount of protein is necessary to saturate the column, owing to its low capacity.