Panel A. Western blot analysis of scFv 32, 43 and 51 bacterial lysates (BL), periplasmic extracts (PE) and soluble total extracts (TE) obtained from equal volumes of bacterial culture after IPTG induction for 4 hours at RT. Panel B. Comassie-blue stained gel after SDS-PAGE (1 and 3) and Western blot analysis (2 and 4) of the periplasmic extract (PE) and of the purified product (Pur) from cultures of M15 E. coli strain expressing the scFv32 as an example. Purification was performed either by NiNTA or Protein A-Sepharose affinity-chromatography as indicated. The scFv detection was performed by the anti-FLAG tag M2 mAb followed by GAM-HRP incubation. Molecular mass markers are shown on the left.