Production of a single-chain antibody against human ferritin in Escherichia coli

We have cloned cDNA copies of the immunoglobulin heavy and light chain genes from hybridoma cells able to produce antibody against human ferritin. Variable segments of these genes were obtained using the polymerase chain reaction (PCR). The specific amplifications of ligase reaction products were carried out to combine the variable segments with DNA fragments coding for a peptide-linker and for a signal peptide of the cloned pelB gene of Erwinia carotovora. During the antiferritin single-chain antibody gene expression under the T7 RNA polymerase control in E. coli the processed molecules of recombinant proteins formed aggregates in periplasm. The reversible denaturation in the absence of reducing agents had allowed us to obtain single-chain antibodies with the original binding specificity toward human ferritin.