A mutant of the polypeptide Protein A, wherein immunoglobulin binding properties can be altered by changing temperature under the conditions of pH 5-9, below 60° C. The use of the mutant Protein A include the use thereof as a ligand coupled to an affinity chromatography support for the purification of immunoglobulins by affinity chromatography, wherein the immunoglobulins is eluted by changing temperature and thereby the conformation of the mutant Protein A.