Peptide models of dynorphin A(1-17) incorporating minimally homologous substitutes for the potential amphiphilic beta strand in residues 7-15.
Two peptide models of dynorphin A(1-17) have been synthesized. These peptides incorporate a minimally homologous substitute sequence for residues 6-17, including alternating lysine and valine residues substituting for the potential amphiphilic beta-strand structure in positions 7-15. Model 1 retains Pro10 from the native sequence, but model 2 does not. Compression isotherms of peptide monolayers at the air-water interface and CD spectra of peptide films adsorbed from aqueous solution onto siliconized quartz slides were evaluated by comparison to those of idealized amphiphilic alpha-helical, beta-sheet, and disordered peptides. Dynorphin A(1-17) was mostly disordered, whereas beta-endorphin was alpha helical. Dynorphin model 1 had properties similar to those of dynorphin A(1-17) at these interfaces, but model 2 formed strongly amphiphilic beta sheets. In binding assays to mu-, delta-, and kappa-opioid receptors in guinea pig brain membranes, model 1 reproduced the high potency and selectivity of dynorphin A(1-17) for kappa receptors, and model 2 was only 3 times less potent and less selective for these receptors. Both peptide models retained the high, kappa-selective agonist activity of dynorphin A(1-17) in guinea pig ileum assays, and like dynorphin A(1-17), model 1 had little activity in the rat vas deferens assay. In view of the minimal homology of the modeled dynorphin structures, these studies support current models of membrane-catalyzed opioid ligand-receptor interactions and suggest a role for the amphiphilic alpha-helical and beta-strand structures in beta-endorphin and dynorphin A(1-17), respectively, in this process.
Taylor
J W
JW
Laboratory of Bioorganic Chemistry and Biochemistry, Rockefeller University, New York, New York 10021.
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004399:Dynorphins / Q000378:metabolism / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism; D013329:Structure-Activity Relationship; D013552:Swine; D014649:Vas Deferens / Q000187:drug effects
D010455:Peptides; D011957:Receptors, Opioid; D004399:Dynorphins