FG beads® with antibodies immobilized on them are mixed with crude cell extract or other solution in order to screen the antigens. After elution of the antigens, analysis by electrophoresis (if necessary) and immunoblot is performed.
The ordinary method of eluting antigens involves heating in a buffer solution that contains melcaptoethanol or other reducing agent. However if this is done, the antibodies which are immobilized on the beads are also eluted, and analysis is difficult when the molecular weights of the antigen and antibody are similar. In order to prevent this, an acidic buffer which does not contain reducing agent is used as the elution buffer in order to elute only the antigens without eluting the antibodies.