Disclosed is a method of isolating a protein from a sample, involving (i) providing a first molecule which is capable of forming an affinity complex with the protein; (ii) contacting the sample with the first molecule under conditions which allow affinity complex formation; (iii) isolating the complex; (iv) treating the complex with a second molecule, the second molecule mimicking an amino acid residue of either the protein or the first molecule which is critical to the complex formation, so that the second molecule disrupts the complex; causing the release of the protein from the complex; and (v) isolating the protein. According to one embodiment, the amino acid mimetic imidazole is used as a very gentle elution reagent to disrupt a protein A-antibody fusion protein complex, a technique which has general application for the isolation of antibodies or recombinant antibody fusion proteins.