title: Structural requirement for the recognition of luteinizing hormone releasing hormone (LHRH) by monoclonal and conventional anti-LHRH antibodies.
abstract: Immunochemical studies on monoclonal and conventional anti-LHRH antibodies have been reported. The association constants (Ka) were in the order of 10(9)-10(10) L/mol when calculated from Scatchard and Steward-Petty plots. Heterogeneity indices (a) calculated from Sips plot were nearly 1.0, indicating the homogeneous nature of monoclonals. Most of the conventional anti-LHRH produced by monkey, baboon, rabbit, and dog, by immunization using LHRH linked to tetanus toxoid by the carbodiimide condensation method, showed a single slope in Scatchard analysis (except two dog antisera) and a values were nearly 1.0. Monoclonals and conventionals reacted most strongly with native LHRH(NH2). Monoclonals showed poor reactivity with LHRH free acid and LHRH fragments containing free acid. The C-terminus tetrapeptide 7-10 showed 10 times more reactivity than tripeptide 4-6. The heptapeptide 4-10 showed 100 and 1000 times more reactivity than the tetra- and tri-peptide, respectively. Introduction of the tripeptide pGlu-His-Trp-OH to heptapeptide 4-10 caused five times more inhibition in reactivity than the heptapeptide. Conventional anti-LHRH antibodies manifested specificity to the C-terminus of LHRH. These sera did not react with LHRH free acid and LHRH fragments of sequence 4-6, 7-10, and 4-10. The complete loss of reactivity of conventional antibodies and poor reactivity of monoclonal antibodies was partly regained when LHRH free acid was coupled to Lys, Lys-MDP, or (Ala)2-tuftsin, suggesting that for monoclonals and conventionals the antigenic determinant was confined to the conformation involving the C-terminus amide of LHRH.
mesh_terms: D000577:Amides; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000915:Antibody Affinity; D000918:Antibody Specificity; D001667:Binding, Competitive; D003429:Cross Reactions; D000939:Epitopes; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology*; D009842:Oligopeptides / Q000276:immunology; D013329:Structure-Activity Relationship
chemical_list: D000577:Amides; D000911:Antibodies, Monoclonal; D000939:Epitopes; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone