Construction, expression and characterisation of a single-chain diabody derived from a humanised anti-Lewis Y cancer targeting antibody using a heat-inducible bacterial secretion vector

Abstract

A single-chain antibody fragment (scFv) of the humanised monoclonal antibody, hu3S193, that reacts specifically with Ley antigen expressed in numerous human epithelial carcinomas was constructed. A five-residue linker joined the C-terminus of the VH and the N-terminus of the VL, which prevented V-domain association into a monomeric scFv and instead directed non-covalent association of two scFvs into a dimer or diabody. The diabody was secreted into the E. coli periplasm using a heat-inducible vector, pPOW3, and recovered as a soluble, correctly processed protein, following osmotic shock or solubilised with 4M urea from the insoluble fraction. The diabody from both fractions was isolated by a..