A sulfanyl-PEG derivative of relaxin-like peptide utilizable for the conjugation with KLH and the antibody production

A small peptide–keyhole limpet hemocyanin (KLH) conjugate is generally used as an antigen for producing specific antibodies. However, preparation of a disulfide-rich heterodimeric peptide–KLH conjugates is difficult. In this study, we developed a novel method for preparation of the conjugate, and applied it to the production of specific antibodies against the relaxin-like gonad-stimulating peptide (RGP) from the starfish. In this method, a sulfanyl group necessary for the conjugation with KLH was site-specifically introduced to the peptide after regioselective disulfide bond formation reactions. Using the conjugate, we could obtain specific antibodies with a high antibody titer. This method might also be useful for the production of antibodies against other heterodimeric peptides with disulfide cross-linkages, such as vertebrate relaxins.