This research will seek to elucidate the interaction between the biophysical chemistry of proteins and the adsorption surfaces used in ion-exchange separations. The study will take a structural, molecular-scale approach through the use of genetic engineering to produce charge-altered forms of a single test protein of known structure. The variation of adsorption isotherm and adsorption thermodynamics resulting from each systematic change in charge groups on the surface of the protein will provide a direct test of the involvement of each protein residue in the adsorption of the protein. Ion Exchange chromatography has already emerged as an important tool in biotechnology. Many of the phenomena related to the adsorption of proteins on ion exchange resins are poorly understood, however, including the tendency of the adsorption process to partially damage the protein, which reduces its usefulness. By using genetic engineering to modify only small regions of the surface of the protein, this project should make a major contribution to the fundamental understanding of the ion exchange of proteins.
