IMIDAZOLE - A NEW LIGAND FOR METAL AFFINITY PRECIPITATION - PRECIPITATION OF KUNITZ SOYBEAN TRYPSIN-INHIBITOR USING CU(II)-LOADED COPOLYMERS OF 1-VINYLIMIDAZOLE WITH N-VINYLCAPROLACTAM OR N-ISOPROPYLACRYLAMIDE

Kunitz soybean trypsin inhibitor (STI) was specifically coprecipitated during precipitation of Cu(II)-loaded copolymers induced by increase in temperature and ionic strength. The copolymers used consisted of 1- vinylimidazole and N-vinylcaprolactam or N-isopropylacrylamide. The el ution of STI was achieved by solubilization of the STI-Cu(II)-polymer complex in the presence of an excess of the competing ligand, imidazol e, and a subsequent precipitation of the polymer with STI remaining fr ee in solution in a purified form as judged by Sodium dodecylsulfate-p olyacrylamide gel electrophoresis (SDS-PAGE). To the best of our knowl edge this is the first reported successful metal affinity precipitatio n of protein in a heterobifunctional format.