title: [Synthesis, biological activity and conformation of enkephalin analogs structurally related to kyotorphin].
abstract: [D-Arg2,Leu5]Enkephalin and two series of its N-terminal short-chain analogues with a free and modified C-terminal carboxylic group, viz. amides and ethyl esters of tri- and tetrapeptides, were synthesized in solution and by solid-phase method. Their analgesic activity, assayed by the "tail pinch" method following intracisternal and intravenous administration to mice, was compared with activity of enkephalins and morphine. To study the space structure of the synthesized compounds, conformational calculations and fluorescence spectroscopy were applied to measure distance between aromatic nuclei of tyrosine and phenylalanine residues in the two tetrapeptides. Ethyl esters of the tri- and tetrapeptides exceed in analgesic activity the corresponding carboxylic acids and amides. In contrast to the pentapeptide, the tetrapeptide analogues were active upon intravenous administration. Conformational aspects of this series of analogues are discussed in detail; the abrupt increase in activity upon transition from tri- to tetrapeptides does not appear to be related to conformational changes.
authors.forename: I V
authors.initials: IV
authors.lastname: Bobrova
authors.forename: N A
authors.initials: NA
authors.lastname: Abissova
authors.forename: L U
authors.initials: LU
authors.lastname: Podin'sh
authors.forename: B G
authors.initials: BG
authors.lastname: Vesterman
authors.forename: G V
authors.initials: GV
authors.lastname: Nikiforovich
mesh_terms: D000700:Analgesics / Q000032:analysis / Q000138:chemical synthesis*; D004151:Dipeptides / Q000032:analysis / Q000138:chemical synthesis; D004723:Endorphins / Q000032:analysis / Q000138:chemical synthesis*; D004745:Enkephalins / Q000032:analysis / Q000138:chemical synthesis*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D000700:Analgesics; D004151:Dipeptides; D004723:Endorphins; D004745:Enkephalins; C019448:kyotorphin
vernacular_title: Sintez, biologicheskaia aktivnost' i konformatsionnye issledovaniia analogov énkefalina, strukturno rodstvennykh kiotrofinu.