Abstract: An affinity carrier may have improved alkali resistance. An immunoglobulin-binding protein containing a mutant polypeptide chain, as well as an affinity carrier containing a solid-phase carrier to which the immunoglobulin-binding protein is bound, may be a mutant polypeptide chain having an amino acid sequence having at least 85% identity to an amino acid sequence indicated by any of SEQ ID NO: 1-6 and 57-62, having a predetermined mutation, and having immunoglobulin-binding activity.

Abstract: To provide an affinity support in which a binding property of a ligand to a target substance is improved. The affinity support contains a solid phase support and a protein ligand, wherein the protein ligand is represented by formula (1): R—R1 (1) wherein R represents a linker binding to the solid phase support, which contains a polyproline, and R1 represents a protein showing an affinity to immunoglobulin, and the R is bound to a C terminal or an N terminal of an amino acid sequence in R1.

Abstract: Provided is an affinity chromatography carrier that maintains high immunoglobulin-binding capacity and high alkali resistance. An immunoglobulin-binding protein including at least one modified immunoglobulin-binding domain, the modified immunoglobulin-binding domain being a polypeptide consisting of an amino acid sequence of an immunoglobulin-binding domain selected from the group consisting of the B domain, Z domain, C domain, and variants thereof of Staphylococcus aureus protein A, in which at least one amino acid residue is inserted between positions corresponding to the 3-position and position 4 of the amino acid sequence of the B domain, Z domain or C domain.

Abstract: To provide an affinity support in which a binding property of a ligand to a target substance is improved. The affinity support contains a solid phase support and a protein ligand, wherein the protein ligand is represented by formula (1): R—R1 (1) wherein R represents a linker binding to the solid phase support, which contains a polyproline, and R1 represents a protein showing an affinity to immunoglobulin, and the R is bound to a C terminal or an N terminal of an amino acid sequence in R1.

Abstract: Provided is an affinity chromatography carrier that maintains high immunoglobulin-binding capacity and high alkali resistance. An immunoglobulin-binding protein including at least one modified immunoglobulin-binding domain, the modified immunoglobulin-binding domain being a polypeptide consisting of an amino acid sequence of an immunoglobulin-binding domain selected from the group consisting of the B domain, Z domain, C domain, and variants thereof of Staphylococcus aureus protein A, in which at least one amino acid residue is inserted between positions corresponding to the 3-position and position 4 of the amino acid sequence of the B domain, Z domain or C domain.