Human catalytic antibody Se-scFv-B3 with high glutathione peroxidase activity

In order to generate catalytic antibodies with glutathione peroxidase (GPX) activity, we prepared GSH‐S‐2,4‐dinitrophenyl t‐butyl ester (GSH‐S‐DNPBu) as target antigen. Three clones (A11, B3, and D5) that bound specifically to the antigen were selected from the phage display antibody library (human synthetic VH + VL single‐chain Fv fragment (scFv) library). Analysis of PCR products using gel electrophoresis and sequencing showed that only clone B3 beared intact scFv‐encoding gene, which was cloned into the expression vector pPELB and expressed as soluble form (scFv‐B3) in Escherichia coli Rosetta. The scFv‐B3 was purified by Ni2+‐immobilized metal affinity chromatography (IMAC). The yield of purified proteins was about 2.0–3.0 mg of proteins from 1 L culture. After the active site serines of scFv‐B3 were converted into selenocysteines (Secs) with the chemical modification method, we obtained the human catalytic antibody (Se‐scFv‐B3) with GPX activity of 1288 U/µmol. Copyright © 2008 John Wiley & Sons, Ltd.