Methods to Measure Binding Equilibria
In equilibrium dialysis, the protein and its ligand are separated by a semi-permeable membrane which allows passage of unbound ligand, but not the protein (see Fig. 43.1). Thus the ligand will diffuse across the membrane until the concentration of free ligand at both sides of the membrane will be identical. Since the RL-complex can not diffuse across the membrane, it will increase the total ligand concentration on the protein side of the membrane. Often, radioactively labelled ligands are used.