| abstract |
Disclosed is a novel modified protein A ligand having superior antibody acid dissociation properties than those of conventional modified protein A ligands. Specifically disclosed is a protein having an affinity for an immunoglobulin, which is characterized by comprising an amino acid sequence which is produced by introducing at least one amino acid residue replacement mutation into an amino acid sequence that is derived from any one of domains E, D, A, B and C in protein A, corresponds to amino acid residues lying between position-31 to position-37 in each of domains A, B and C (amino acid residues lying between position-29 to position-35 in domain E, and amino acid residues lying between position-34 to position-40 in domain D) in protein A and is conserved in all of domains E, D, A, B and C in protein A, and which is also characterized by having a reduced affinity for an Fab region in the immunoglobulin compared with a protein comprising the amino acid sequence in which the mutation is not introduced yet. |