title: Preparation and characterization of photoreactive derivatives of GnRH. Persistent activation of function by photoaffinity labeling.
abstract: A photoreactive derivative of the highly potent gonadotropin releasing hormone (GnRH) agonist, D-Lys6-GnRH(1-9)-ethylamide, was prepared by selective modification of the epsilon-amino group with 2-nitro-4-azidophenyl sulfenyl chloride (2,4-NAPS C1). The modified peptide [D-Lys(NAPS)]6-GnRH-(1-9)-ethylamide was found to be a full agonist of LH release from rat pituitary cells with a relative potency 23 compared to GnRH. Covalent attachment of the photoreactive analog to rat pituitary cells resulted in prolonged activation of LH secretion which could not be inhibited by a potent GnRH antagonist. Persistent stimulation of pituitary gonadotrophs caused by covalently bound hormone led to desensitization of the LH releasing mechanism.
mesh_terms: D000345:Affinity Labels / Q000138:chemical synthesis; D000818:Animals; D002478:Cells, Cultured; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D010777:Photochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism; D011966:Receptors, LHRH
chemical_list: D000345:Affinity Labels; D011956:Receptors, Cell Surface; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone