Method for purifying protein

Abstract

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 performing filtration using a porous membrane having a graft chain on a pore surface and an anion-exchange group fixed to the graft chain.

1 . A method for purifying a protein to remove impurities from a mixture liquid containing a desired protein and the impurities, comprising:
 performing filtration using a porous membrane having a graft chain on a pore surface and an anion-exchange group fixed to the graft chain.   
     
     
         2 . The method for purifying the protein according to  claim 1 , wherein the desired protein is one selected from the group consisting of monoclonal antibodies, polyclonal antibodies, humanized antibodies, human antibodies, and immunoglobulins. 
     
     
         3 . The method for purifying the protein according to  claim 1 , wherein the impurities are at least one selected from the group consisting of a non-turbid component and a turbid component dispersed in the mixture liquid. 
     
     
         4 . The method for purifying the protein according to  claim 3 , wherein the non-turbid component is at least one selected from the group consisting of impurity proteins, HCP, DNA, viruses, endotoxins, proteases, and bacteria dissolved in the mixture liquid. 
     
     
         5 . The method for purifying the protein according to  claim 3 , wherein the turbid component dispersed in the mixture liquid is at least one selected from the group consisting of cells and cell debris. 
     
     
         6 . The method for purifying the protein according to  claim 1 , wherein a salt concentration of the mixture liquid is from 0.01 M to 0.5 M (both inclusive). 
     
     
         7 . The method for purifying the protein according to  claim 6 , wherein the salt concentration of the mixture liquid is from 0.1 M to 0.3 M (both inclusive). 
     
     
         8 . The method for purifying the protein according to  claim 1 , wherein:
 a base material of the porous membrane is polyethylene or polyvinylidene fluoride,   the graft chain is a polymer of glycidyl methacrylate and has a graft rate of from 10% to 250% (both inclusive), and   the graft chain has 70% or more of epoxy groups replaced with the anion-exchange groups.   
     
     
         9 . The method for purifying the protein according to  claim 8 , wherein the graft rate is from 10% to 150% (both inclusive). 
     
     
         10 . The method for purifying the protein according to  claim 8 , wherein the graft rate is from 10% to 90% (both inclusive). 
     
     
         11 . The method for purifying the protein according to  claim 8 , wherein the graft rate is from 30% to 60% (both inclusive). 
     
     
         12 . The method for purifying the protein according to  claim 1 , wherein the anion-exchange group is a diethylamino group and/or a trimethylamino group. 
     
     
         13 . The method for purifying the protein according to  claim 1 , wherein the anion-exchange group is a diethylamino group. 
     
     
         14 . The method for purifying the protein according to  claim 1 , wherein the porous membrane has a maximum pore size of from 0.1 μm to 0.8 μm (both inclusive). 
     
     
         15 . The method for purifying the protein according to  claim 1 , wherein the mixture liquid is filtered using the porous membrane to remove one or more impurities comprising a non-turbid component. 
     
     
         16 . The method for purifying the protein according to  claim 1 , wherein the mixture liquid is an animal cell culture. 
     
     
         17 . The method for purifying the protein according to  claim 1 , wherein the porous membrane is a porous hollow fiber membrane. 
     
     
         18 . The method for purifying a protein according to  claim 1 , further comprising performing purification using affinity chromatography.