title: Phosphorylation of enkephalins: NMR and CD studies in aqueous and membrane-mimicking environments.
abstract: Phosphorylation of l-serine-containing enkephalin analogs has been explored as an alternative to glycosylation in an effort to increase blood-brain barrier permeability and CNS bioavailability of peptide pharmacophores. Two enkephalin-based peptides were modified for these studies, a set related to DTLES, a mixed μ/δ-agonist, and one related to DAMGO, a highly selective μ-agonist. Each unglycosylated peptide was compared to its phosphate, its mono-benzylphosphate ester, and its β-d-glucoside. Binding was characterized in membrane preparations from Chinese hamster ovary cells expressing human μ, δ and κ-opiate receptors. Antinociception was measured in mice using the 55 °C tail-flick assay. To estimate bioavailability, the antinociceptive effect of each opioid agonist was evaluated after intracerebroventricular (i.c.v.) or intravenous administration (i.v.) of the peptides. Circular dichroism methods and high-field nuclear magnetic resonance were used in the presence and absence of sodium dodecylsulfate to understand how the presence of a membrane might influence the peptide conformations.
authors.affiliation: Carl S. Marvel Laboratories, Department of Chemistry and Biochemistry, BIO5, The University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Larisa
authors.initials: L
authors.lastname: Yeomans
authors.forename: Dhanasekaran
authors.initials: D
authors.lastname: Muthu
authors.forename: John J
authors.initials: JJ
authors.lastname: Lowery
authors.forename: Heather N
authors.initials: HN
authors.lastname: Martinez
authors.forename: Leif
authors.initials: L
authors.lastname: Abrell
authors.forename: Guanxin
authors.initials: G
authors.lastname: Lin
authors.forename: Kyle
authors.initials: K
authors.lastname: Strom
authors.forename: Brian I
authors.initials: BI
authors.lastname: Knapp
authors.forename: Jean M
authors.initials: JM
authors.lastname: Bidlack
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Bilsky
authors.forename: Robin
authors.initials: R
authors.lastname: Polt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism; D016466:CHO Cells; D002490:Central Nervous System / Q000378:metabolism; D002942:Circular Dichroism; D006224:Cricetinae; D004745:Enkephalins / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010147:Pain Measurement; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D004745:Enkephalins; D010455:Peptides; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D014867:Water; D012967:Sodium Dodecyl Sulfate