2.5 Sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS-PAGE) analysis
Medium samples (10 µL) harvested from semi-continuous cultures were
mixed with SDS sample buffer (5 µL) with or without 2-melcaptoethanol
and boiled for 5 min. Sample solutions were electrophoresed on 4%–20%
precast polyacrylamide gels (#4561094; BioRad, Hercules, CA, USA).
Protein bands were visualized by incubating gels in protein staining
solution (#LC6060, SimpleBlue SafeStain, Invitrogen) for 1 h. Next,
gels were immersed in distilled water for 2 days to remove excess dye.
Purified scFv-Fc was prepared from culture medium using a Protein A
Sepharose column (rProtein A Sepharose Fast Flow, #17127901; Cytiva,
Marlborough, MA, USA).[31]