Preparation of dimerized polypeptide-carrying microspheres and purification of specific proteins bound to these microspheres

We have developed polypeptide-carrying microspheres for bioaffinity separation. The carrier microspheres were composed of a polystyrene core and a poly(glycidyl methacrylate) surface layer on which ethyleneglycol diglycidyl ether was introduced as a spacer. The epoxy group of the spacer's end was hydrolyzed. The hydroxy end group was then activated by tosyl(p-toluenesulfonyl) chloride. To tosyl-group-carrying microspheres, we immobilized a polypeptide, HT-Lys₅-N236, which contains the carboxyl terminal region of transcription factor hGABP β, analyzed the structure of the polypeptide immobilized on the surface of microspheres and used these hybrid microspheres for the purification of N236-binding protein from HeLa cell nuclear extracts directly and from the fractions separated with a phosphocellulose column.