PRODUCTION OF SEQUENCE-SPECIFIC POLYCLONAL ANTIBODIES TO HUMAN PARATHYROID-HORMONE-1-37 BY IMMUNIZATION WITH MULTIPLE ANTIGENIC PEPTIDES

To generate site-specific antibodies to the N-terminal bioactive fragm ent of the parathyroid hormone hPTH 1-37, multiple antigenic peptide s ystems (MAP) for immunization were used. Two 10 residue fragments and a 13 residue fragment derived from knowledge of the secondary structur e of hPTH 1-37 were selected to be synthesized as MAPs. Each peptide ( hPTH 1-10, hPTH 9-18, and hPTH 24-37) was synthesized directly onto a branching heptalysine core matrix by automated solid phase synthesis. The hPTH 1-10 and the hPTH 24-37 MAP were highly immunogenic in rabbit s. Ten polyclonal antisera obtained from rabbits were characterized by epitope mapping. Antigenic determinants were found as follows: 1) Ser a K-1-K-3 raised to MAP 1-10 showed a predominant binding sequence at hPTH 1-5. 2) Sera K-(4)-K-6 raised to MAP 8-18 preferentially bound to residues 9-14. 3) Immunizing with hPTH 24-37 MAP led to antisera char acterized as follows: serum K-7 recognized residues 24-37, the sequenc e used for immunization, sera K8, K9 and K10 bound to residues 24-37 a nd 26-34. In summary, the favoured regions as deduced from the seconda ry structure of hPTH 1-37 were covered by the produced antibodies.