Immunospecificity and affinity studies on the monoclonal anti-gonadotropin releasing hormone (GnRH) antibodies: monoclonals produced by azotized GnRH preferentially recognise to native GnRH.

Monoclonal anti-GnRH(MoAb) antibodies generated by using azo-GnRH-TT conjugate were purified by affinity chromatography using azo-GnRH-BSA-Sepharose 4B column. The affinity column bound (A-MoAb) and unbound (U-MoAb) fractions were tested for immunoreactivity towards GnRH(NH2), azo-GnRH(NH2) and GnRH free acid and its fragments of sequence 4-6, 7-10 and 4-10. Both fractions reacted best with native GnRH and about 20 times less to azo-GnRH. The cross-reactivity with other GnRH(OH) fragments and affinity characteristics of A-MoAb, and U-MoAb was comparable with those of MoAb. The immunoreactivity of both the fractions was regained when C-terminus of GnRH free acid was blocked by MDP-Lys, Lys or Ala-Ala-Thr-Lys-Pro-Arg-OH indicating the importance of C-terminus amide in the recognition ability of antibodies.