Immunoaffinity chromatography in biorecovery: an application of recombinant DNA technology to generic adsorption processes.

The constant region of human kappa light chain (Ck) was linked to Escherichia coli beta-galactosidase, using standard molecular cloning techniques. The binding of Ck-beta-galactosidase fusions to a number of different murine monoclonal antibodies, specific for Ck, was improved by the insertion of spacers between Ck and beta-galactosidase: a cleavable linker was then introduced. Over-expressed Ck-beta-galactosidase fusion protein was purified using monoclonal antibodies immobilised on Sepharose 4B. Elution conditions were found that maintained beta-galactosidase activity so purified enzyme could be released on breaking the cleavable linker. A number of practical problems associated with maintaining stable fusion proteins and immunoaffinity column performance were identified.