Electrophoretic immunodesorption of proteins according to molecular weightby use of a double-membrane system

A simple method is described for electrophoretic desorption of proteins fro m antigen-antibody complexes, with more than 90 % recovery and without dena turation, after immunosorbent affinity chromatography. Radiolabeled or unla beled human serum albumin (HSA) and alpha-1-antitrypsin (AAT), conjugated t o rabbit anti-HSA or anti-AAT polyclonal antisera, respectively, were elect rophoretically desorbed from Sepharose 4B. In addition, purification and co ncentration of the major HSA protein band (monomer) of 68 kD from the other oligomeric protein bands were achieved by use of a two-membrane system in a simple electroelution apparatus. The system consisted of an upper cellulo se acetate membrane, with pore size 20 nm and separation limit 70 kD, and a lower dialysis cellophane membrane with molecular weight cut-off from 1-50 kD that enables separation according to size. Furthermore, purification of the monomer HSA or AAT from normal human serum was performed with 92% reco very. Homogeneity was implied by the presence of one band after sodium dode cyl sulfate (SDS)-polyacrylamide gel electrophoresis. Western blot, and aut oradiography.