title: Synthesis and evaluation of isothiocyanate-containing derivatives of the delta-opioid receptor antagonist Tyr-Tic-Phe-Phe (TIPP) as potential affinity labels for delta-opioid receptors.
abstract: Derivatives of the delta-opioid receptor-selective peptide antagonist H-Tyr-Tic-Phe-Phe-OH (TIPP) containing an isothiocyanate moiety at the para position of either Phe(3) or Phe(4) were prepared as potential affinity labels for delta-opioid receptors. The synthesis was accomplished using a general solution-phase synthetic procedure which allows for introduction of affinity labeling groups late in the synthesis of a variety of small peptide substrates. The target peptides and their corresponding amines were then evaluated in radioligand binding experiments using Chinese hamster ovary (CHO) cells expressing delta- and mu-opioid receptors. The peptides [Phe(p-NCS)(3)]TIPP (2) and [Phe(p-NCS)(4)]TIPP (4) showed affinity for delta-receptors comparable to the parent compound TIPP (IC(50) = 12 and 5 nM, respectively, vs 6 nM for TIPP). Both peptides 2 and 4 were able to inhibit radioligand binding to delta-receptors in a wash-resistant manner at a concentration of 10 nM. Therefore, the peptides [Phe(p-NCS)(3)]TIPP (2) and [Phe(p-NCS)(4)]TIPP (4) represent two affinity labels that may prove useful in the study of delta-opioid receptors.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA.
authors.forename: D Y
authors.initials: DY
authors.lastname: Maeda
authors.forename: F
authors.initials: F
authors.lastname: Berman
authors.forename: T F
authors.initials: TF
authors.lastname: Murray
authors.forename: J V
authors.initials: JV
authors.lastname: Aldrich
mesh_terms: D000345:Affinity Labels / Q000138:chemical synthesis* / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D017879:Isothiocyanates / Q000138:chemical synthesis* / Q000378:metabolism; D051379:Mice; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000378:metabolism; D044005:Tetrahydroisoquinolines; D014162:Transfection
chemical_list: D000345:Affinity Labels; D017879:Isothiocyanates; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D044005:Tetrahydroisoquinolines; C419184:tyrosyl--1,2,3,4--tetrahydroisoquinoline-3-carbonyl-phenylalanyl-4-isothiocyanatophenylalanine; C419183:tyrosyl--1,2,3,4-tetrahydroisoquinoline-3-carbonyl-4-isothiocyanatophenylalanyl-phenylalanine; C082263:tyrosyl-1,2,3,4-tetrahydro-3-isoquinolinecarbonyl-phenylalanyl-phenylalanine