Protein purification method

A method of recovering a protein or polypeptide of interest, the method comprising

• (a) immobilizing, on a solid support, an antibody raised against a peptide which comprises at least a fragment comprising an antigenic determinant of said protein or polypeptide,
• (b) contacting a crude preparation of the protein or polypeptide of interest with the immobilized antibody under conditions resulting in a partial, reversible unfolding of the protein or polypeptide, so as to expose an amino acid sequence therein corresponding to the peptide used for raising the immobilized antibody and thereby obtain binding of the protein or polypeptide to the antibody, wherein the conditions resulting in a partial, reversible unfolding of the protein or polypeptide in step (b) are selected from a group consisting of an increase in temperature to between 37.degree. and 60.degree. C., a substantial increase or decrease in the pH of the protein or polypeptide preparation relative to the pH at which the protein or polypeptide is functional, the addition of a protein denaturing agent to the protein or polypeptide preparation, a concentration of a salt in the protein or polypeptide preparation higher than the physiological concentration of the salt, or a combination of two or more of these measures, and
• (c) eluting the protein or polypeptide from the solid support under non-denaturing conditions to recover said protein or polypeptide in a form in which it is refolded into its native conformation.