Competitive adsorption of α-lactalbumin and bovine serum albumin to a sulfopropyl ion-exchange membrane

Abstract

Breakthrough curves were measured for pure solutions of α-lactalbumin (ALA) and bovine serum albumin (BSA) individually, and for a binary mixture of the proteins, using a sulfopropyl ion-exchange membrane. The breakthrough curves were qualitatively consistent with local-equilibrium theory predictions. Competitive adsorption caused displacement of bound BSA monomer by the more strongly binding BSA dimer, illustrating that even apparently single-protein systems may display multicomponent competitive behavior. In the two-protein experiment, ALA was competitively displaced by the more strongly binding BSA monomer and dimer, indicating that the binding strength was in the order: BSA dimer > BSA monomer > ALA.