Abstract: A method for filtering a protein-containing liquid containing protein at a concentration of 20 mg/mL or more and 100 mg/mL or less, the method including a prefiltration step of filtering the protein-containing liquid by a prefilter having a pore size of 0.08 ?m to 0.25 ?m and including a hydrophobic resin, and a virus removal step of filtering the protein-containing liquid by a virus removal membrane including a synthetic polymer, after the prefiltration step, wherein the protein-containing liquid before conducting the prefiltration step includes 0.25 g or more of a trimer or higher multimer of the proteins having an average diameter of less than 100 nm, per 1 m2 of the virus removal membrane.

Abstract: A method for filtering a protein-containing liquid containing protein at a concentration of 20 mg/mL or more and 100 mg/mL or less, the method including a prefiltration step of filtering the protein-containing liquid by a prefilter having a pore size of 0.08 ?m to 0.25 ?m and including a hydrophobic resin, and a virus removal step of filtering the protein-containing liquid by a virus removal membrane including a synthetic polymer, after the prefiltration step, wherein the protein-containing liquid before conducting the prefiltration step includes 0.25 g or more of a trimer or higher multimer of the proteins having an average diameter of less than 100 nm, per 1 m2 of the virus removal membrane.

Abstract: A method for purifying a biologically active substance from a solution mixture containing impurities and the biologically active substance, in which an ion exchange chromatography carrier comprising a matrix and a copolymer containing at least N-isopropylacrylamide as a monomer unit and immobilized to a surface of the matrix is used, and the solution mixture is allowed to flow through a container storing the carrier at a uniform temperature, thereby recovering the biologically active substance.

Abstract: The present invention provides a method for purifying a protein, comprising: providing a solution containing a monomer and aggregates of the protein of interest; a purification step of removing the aggregates of the protein of interest using a cation-exchange chromatographic support media to obtain a purified solution of the monomer, the cation-exchange chromatographic support media comprising at least one type of weak cation-exchange group and having a cation-exchange group density higher than 30 mmol/L; and a virus removal step of removing viruses from the purified solution using a virus removal membrane having a virus logarithmic reduction value of 3 or more.

Abstract: A method is disclosed for purifying an antibody monomer, comprising providing a porous membrane comprising a hydrophobic porous substrate, a hydrophilic molecular chain of a different material from that of the porous substrate, immobilized on the surface of pores of the porous substrate, and a side chain of the molecular chain, containing a nitrogen atom to which one to three alkyl groups each having two or three carbon atoms are bonded; passing an antibody solution containing antibody aggregates of dimers or higher-order multimers through the porous membrane to adsorb the antibody aggregates to the porous membrane; and recovering the purified antibody monomer in the passed solution.

Abstract: A method for purifying a biologically active substance from a solution mixture containing impurities and the biologically active substance, in which an ion exchange chromatography carrier comprising a matrix and a copolymer containing at least N-isopropylacrylamide as a monomer unit and immobilized to a surface of the matrix is used, and the solution mixture is allowed to flow through a container storing the carrier at a uniform temperature, thereby recovering the biologically active substance.

Abstract: A method is disclosed for purifying an antibody monomer, comprising providing a porous membrane comprising a hydrophobic porous substrate, a hydrophilic molecular chain of a different material from that of the porous substrate, immobilized on the surface of pores of the porous substrate, and a side chain of the molecular chain, containing a nitrogen atom to which one to three alkyl groups each having two or three carbon atoms are bonded; passing an antibody solution containing antibody aggregates of dimers or higher-order multimers through the porous membrane to adsorb the antibody aggregates to the porous membrane; and recovering the purified antibody monomer in the passed solution.