Antibody purification method, antibody obtained therefrom, novel antibody purification method using cation exchanger, and antibody obtained therefrom

A method for purifying a target substance, the method comprising:

• applying a solution containing the target substance to a column, wherein the column comprises a first carrier comprising an affinity ligand which has affinity to the target substance and a second carrier comprising a cation exchange group;
• passing an elution solution through the column, thereby eluting the target substance,
• wherein the target substance is immunoglobulin G, an immunoglobulin G derivative, a Fc-containing molecule, Fab, scFv, a diabody, or a molecule containing a binding part capable of binding to an antigen,
• wherein the column is an integrated column having a first column having the first carrier and a second column having the second carrier, or a single column having a mixture of the first carrier and the second carrier,
• wherein the first column is connected to the second column such that the second column is positioned downstream of the first column,
• wherein the applying and the passing are carried out from upstream to downstream of the integrated column or the single column,
• wherein affinity chromatography and cation exchange chromatography are performed at one chromatography step, and
• wherein a pKa of the cation exchange group is equal or greater than a pH of the elution solution, and the pKa of the cation exchange group is 4.0 or more and the pH of the elution solution is 4.0 or less.