Patent 8653246 was granted and assigned to Asahi Kasei on February, 2014 by the United States Patent and Trademark Office.
The present invention provides a method for purifying a protein to remove impurities from a mixture liquid containing a desired protein and the impurities, comprising the step of performing filtration using a porous membrane having a graft chain on a pore surface and an anion-exchange group fixed to the graft chain.