Affinity separation matrix protein

PROBLEM TO BE SOLVED: To provide a novel technology for creating a novel modified protein ligand that maximizes the binding capacity and binding efficiency to a target molecule when a protein ligand is immobilized via a lysine residue (an e-amino group of a side chain) that enables an efficient carrier immobilization reaction.SOLUTION: There are provided a modified protein for protein A, which is a representative affinity purification protein ligand, the protein comprising a sequence in which all lysine residues in the protein are substituted with other amino acids and lysine is added to the end thereof, and an affinity purification matrix in which such a modified protein is immobilized on a water-soluble carrier by reductive amination. The affinity separation matrix has a high binding capacity to a target molecule with a small amount of ligand immobilization.SELECTED DRAWING: None