A U.S. Patent Application for “Ion Exchange Membrane Chromatography” was published by Genentech on April 2nd, 2020. The present invention are methods of enhancing efficiency of downstream chromatography steps for purification of proteins comprising: (a) passing a composition comprising a polypeptide of interest and various contaminants through an ion exchange membrane, wherein the polypeptide and the membrane have opposite charge, at operating conditions comprised of a buffer having a pH sufficiently distinct from the pi of the polypeptide to enhance the charge of the polypeptide and a low ionic strength effective… Learn More