METHIONINE ENKEPHALIN AND ISOSTERIC ANALOGS .2. RECEPTOR CONFORMATION OF METHIONINE ENKEPHALIN

  • 1 January 1980
    • journal article
    • research article
    • Vol. 15 (2), 122-129
Abstract
Biological activities [guinea-pig ileum assay and rat brain synaptosome membrane binding] are reported for 2 different types of analogs of Met-enkephalin. Cyclic analogs, bridged between the amino- and carboxy- terminals of the parent peptide, are inactive. Significant levels of activity are displayed by linear isosterically modified analogs in which the Tyr1-Gly2 peptide bond is replaced by either -CH2NH- or -CH2CH2- Similar replacements of the Gly2-Gly3 peptide bond yield compounds with much reduced potency. These modifications serve as useful probes of the receptor conformation. Based on these findings, a model is proposed for interaction between enkephalin and its receptor.