Ligand and protein fishing with heat shock protein 90 coated magnetic beads.

Heat shock protein 90alpha (Hsp90alpha) is a molecular chaperone that has been targeted for the development of new anticancer therapies. To date, co-immunoprecipitation (IP) has been primarily used to identify novel client proteins. We now report an alternative approach in which Hsp90alpha has been immobilized onto the surface of silica-based magnetic beads. The beads were used to isolate known Hsp90alpha ligands from a mixture containing ligands and nonligands. In addition, they were also used to isolated proteins from a mixture of proteins, as well as a cellular extract. The results indicate that the Hsp90alpha coated magnetic beads can be used to "fish" from complex chemical and biological mixtures for new lead drug candidates and client proteins.