Protein Expression and Purification, Vol.84, No.1, 140-146, 2012
Cloning, expression, purification, and characterization of a novel single-chain variable fragment antibody against the 2-nitrobenzaldehyde derivative of a furaltadone metabolite in Escherichia coli
Furaltadone is an illicit veterinary drug that shows toxic, carcinogenic, and mutagenic effects, as does its metabolite 3-amino-5-morpholinomethyl-2-oxazolidone (AMOZ)(1). Recombinant antibodies with desirable affinity and specificity that can replace polyclonal or monoclonal antibodies are important factors for effective AMOZ immunoassays. In the present study, a novel single-chain variable fragment (scFv) antibody against the 2-nitrobenzaldehyde derivative of AMOZ (NPAMOZ) was prepared and characterized. The scFv gene was cloned into the pET-22b(+) expression vector, and 6His-tagged scFv antibodies expressed as inclusion bodies in Escherichia coil BL21 (DE3), which were then purified by nickel nitrilotriacetic acid column chromatography. Characterization of the target protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), western blotting, and a novel indirect competitive chemiluminescence enzyme immunoassay (icCLEIA) showed that the scFv antibody was similar to 27 kDa and exhibited HRP-anti-His-tag anti-body-recognized activity. The final purity, yield and mg of this scFv antibody after ultrafiltration concentration were 97%, 20% and 29.1 mg, respectively. The icCLEIA indicated that the antibody competitively combined with NPAMOZ, exhibiting an IC50 value of 1.46 +/- 0.01 ng/ml (n = 6). Cross-reactivity studies revealed that the antibody showed desirable specificity to NPAMOZ and little reactivity to analogs except the parent furaltadone. In summary, these findings suggested that the prepared recombinant scFv antibody can be used for future immunoassay screening for AMOZ. (c) 2012 Elsevier Inc. All rights reserved.
Keywords:3-Amino-5-morpholinomethyl-2-oxazolidone;Single-chain Fv antibody;Protein preparation;Protein characterization;Indirect competitive chemiluminescence enzyme immunoassay