title: [Synthesis and analysis of potent cyclic analogs of the ACTH active center].
abstract: Linear and cyclic analogues of the specific active center of the ACTH molecule have been synthesized, viz. [Lis5]ACTH-(5-10)-, [Lys5, cyclo (Gly10----epsilon Lys5)]-ACTH-(5-10)-hexapeptides, [Lys5 (Gly)]ACTH-(5-10)- and [Lys5, Gly11, cyclo (Gly11----epsilon Lys5)]-ACTH-(5-11)-heptapeptides. The cyclic structures are fixed by covalent bond between the COOH-group of the C-terminal glycine and epsilon-amino group of a lysine residue. Azide method, DCC/HOBT or pentafluorophenyl esters are used for fragment coupling, while cyclization is achieved by means of diphenylphosphoryl azide or pentafluorophenyl esters. Cyclic compounds are 2-3 orders of magnitude more active than their linear counterparts as revealed by assaying their melanocyte-stimulating activity in vitro on frog skin. Only the title heptapeptide possesses a steroidogenic activity similar to that of ACTH-(5-10)-hexapeptide. The results obtained are in accord with the idea implying the formation in the hormone-receptor complexes of quasi-cyclic structures in the region of the specific active center of ACTH molecule.
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D066298:In Vitro Techniques; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism; D011896:Rana temporaria; D051381:Rats; D013256:Steroids / Q000096:biosynthesis; D013329:Structure-Activity Relationship
chemical_list: D013256:Steroids; D000324:Adrenocorticotropic Hormone
vernacular_title: Sintez i issledovanie vysokoaktivnykh tsiklicheskikh analogov aktivnogo tsentra kortikotropina.