Provided are methods for modifying the isoelectric point of an antibody while retaining its antigen-binding activity, comprising modifying the charge of at least one exposable amino acid residue on the surface of the complementarity determining region (CDR). Also provided are methods for purifying multispecific antibodies, comprising modifying isoelectric point, and methods for improving the plasma pharmacokinetics of antibodies with a modified isoelectric point. Antibodies with a modified isoelectric point, pharmaceutical compositions comprising the antibodies as an active ingredient, and methods for producing the antibodies and compositions are also disclosed.
