Abstract: An object of the present invention is to provide a polypeptide having a high binding capacity for an immunoglobulin kappa chain, and having excellent alkali stability, by modifying an amino acid sequence of an immunoglobulin-binding domain of Protein L derived from Peptostreptococcus magnus. A polypeptide having a high binding capacity for an immunoglobulin kappa chain, and having excellent alkali stability can be obtained by substituting specific lysine residues in an immunoglobulin-binding domain of Protein L derived from Peptostreptococcus magnus 3316 strain, with a basic amino acid or a hydroxyl group-containing amino acid.

Abstract: A multimeric immunoglobulin-binding protein having improved properties as an affinity ligand for affinity chromatography, and an insoluble support immobilizing such a multimer. The immunoglobulin-binding protein is represented by the formula: (R1)n-(R2)m, or (R2)m-(R1)n. R2 is an immunoglobulin-binding domain including an amino acid residue that covalently bonds to an insoluble support upon immobilization reaction with the insoluble support, and R1 is an immunoglobulin-binding domain without containing an amino acid residue the presence of which in the sequence compared to when it is absent in the sequence reduces the immunoglobulin-binding activity of the support yielded by the immobilization reaction. The immunoglobulin-binding protein satisfies: (1) n is an integer of 5 to 9; (2) m is an integer of 1 or 2; (3) the n (R1) domains may or may not have the same sequence; and (4) the total number of domains (n+m) is 6 to 10.

Abstract: A multimeric immunoglobulin-binding protein having improved properties as an affinity ligand for affinity chromatography, and an insoluble support inmmobilizing such a multimer. The immunoglobulin-binding protein is represented by the formula: (R1)n-(R2)m, or (R2)m-(R1)n. R2 is an immunoglobulin-binding domain including an amino acid residue that covalently bonds to an insoluble support upon immobilization reaction with the insoluble support, and R1 is an immunoglobulin-binding domain without containing an amino acid residue the presence of which in the sequence compared to when it is absent in the sequence reduces the immunoglobulin-binding activity of the support yielded by the immobilization reaction. The immunoglobulin-binding protein satisfies: (1) n is an integer of 5 to 9; (2) m is an integer of 1 or 2; (3) the n (R1) domains may or may not have the same sequence; and (4) the total number of domains (n+m) is 6 to 10.

Abstract: Provided is affinity chromatography carrier for an immunoglobulin that simultaneously has high immunoglobulin-binding capability and chemical stability and that can be produced at low cost. An immunoglobulin-binding protein in which an amino acid substitution for not only maximizing the number of lysine residues on the protein surface of helix 3 and its periphery but also minimizing the number of lysine residues present on the protein surfaces of helix 1 and helix 2 as immunoglobulin-binding regions and/or an amino acid substitution for eliminating an aspartic acid-proline sequence have (has) been carried out, or a multimer thereof, is used as an affinity ligand for an affinity chromatography carrier.

Abstract: Provided is affinity chromatography carrier for an immunoglobulin that simultaneously has high immunoglobulin-binding capability and chemical stability and that can be produced at low cost. An immunoglobulin-binding protein in which an amino acid substitution for not only maximizing the number of lysine residues on the protein surface of helix 3 and its periphery but also minimizing the number of lysine residues present on the protein surfaces of helix 1 and helix 2 as immunoglobulin-binding regions and/or an amino acid substitution for eliminating an aspartic acid-proline sequence have (has) been carried out, or a multimer thereof, is used as an affinity ligand for an affinity chromatography carrier.