Polypeptide linkers suitable for the efficient production of dimeric scFv in Escherichia coli

Single chain variable fragment antibodies (scFvs) were selected from a phage library displaying scFvs consisting of the VH and VL domains of an anti-bisphenol A monoclonal antibody and 20 randomized amino acids linkers by biopanning using an antigen bisphenol A. After four rounds of biopanning selections, seven scFvs with different polypeptide linkers were isolated. The scFvs expressed by the Escherichia coli transformants predominantly formed dimeric structures, and were found in soluble fractions at higher concentrations than those of scFvs containing flexible linkers (G4S)1–3, because the transformants expressing these scFvs could grow to higher cell concentration after the induction of scFv production with IPTG. Consequently, five times higher productivities of soluble scFvs were attained compared with scFvs having the flexible linkers. The antigen binding activities of these scFvs were confirmed by affinity chromatography using an antigen-coupled column and ELISA. The selected polypeptide linkers will be useful for the production of soluble scFv dimers in E. coli.