Hybridoma cells capable of producing antibodies against human ferritin
were used for cloning cDNA copies of immunoglobulin heavy and light c
hain genes. By means of the polymerase chain reaction (PCR) we obtaine
d the variable segments of these genes. Specific amplifications of the
ligase reaction products were performed to combine the variable segme
nts with the DNA fragments encoding the peptide linker and the signal
peptide of the cloned Erwinia carotovora pelB gene. Upon expression of
the gene encoding the single-chain antiferritin antibodies under cont
rol of T7 RNA polymerase in Escherichia coli, the processed molecules
of recombinant proteins formed aggregates in the periplasm of producin
g cells. Reversible denaturation in the absence of reducing agents all
owed us to obtain single-chain antibodies with the original binding sp
ecificity to human ferritin.