STUDY OF PROTEIN TRANSMISSION THROUGH ULTRAFILTRATION MEMBRANES

This paper presents a study of protein transmission through ultrafiltration membranes in a vortex flow filtration unit. Pure dilute solutions of one peptide, the antibiotic bacitracin (1.4 kDa), and three proteins, viz. cytochrome c (12.3 kDa), lysozyme (14.3 kDa) and myoglobin (17.8 kDa), in the appropriate buffers were ultrafiltered through Membrex Ultrafilic(TM) membranes with a molecular weight cutoff of 10 and 100 kDa. The variation in protein transmission with the applied pressure for the 10 kDa membrane follows a trend which can be explained by a combined concentration polarization-irreversible thermodynamics approach. However, ultrafiltration with 100 kDa membranes surprisingly exhibits up to 120% protein transmission for cytochrome c and lysozyme. The enrichment of protein in the permeate can be explained either by a modified concentration polarization theory or a reasoning similar to Sourirajan's preferential sorption-capillary flow mechanism for reverse osmosis.