Measurement and theoretical modeling of protein mobility through membranes

The electrophoretic mobilities of hemoglobin and lysozyme were measured thr ough polycarbonate track-etched membranes of different pore sizes. Together with the zeta potential of the protein-fouled membranes, and measurements of the free-solution mobilities, protein sizes, and membrane pope sizes, th e theory of Ennis et al. was tested, The presence of the membrane offered l ittle hindrance to protein transfer when the membrane pore size was large i n comparison with the protein size and the thickness of the electrical doub le layers. Under some solution conditions, protein agglomeration was signif icant and the interactions between the larger particles, and the membrane p ore walls caused a more pronounced reduction in the protein mobility from i ts free-solution value. Good agreement with the theoretical model was found only for cases where the solution remained as a monodispersed suspension o f protein monomers.