Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

/sup 3/H)-(H-D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2) ((/sup 3/H)CTOP), a potent and highly selective peptide for mu opioid receptors in rat brain

Journal Article · · J. Pharmacol. Exp. Ther.; (United States)
OSTI ID:6470418
; ; ; ; ; ; ; ;
The cyclic, conformationally restricted octapeptide (3H)-(H-D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2) ((3H)CTOP) was synthesized and its binding to mu opioid receptors was characterized in rat brain membrane preparations. Association rates (k+1) of 1.25 x 10(8) M-1 min-1 and 2.49 x 10(8) M-1 min-1 at 25 and 37 degrees C, respectively, were obtained, whereas dissociation rates (k-1) at the same temperatures were 1.93 x 10(-2) min-1 and 1.03 x 10(-1) min-1 at 25 and 37 degrees C, respectively. Saturation isotherms of (3H)CTOP binding to rat brain membranes gave apparent Kd values of 0.16 and 0.41 nM at 25 and 37 degrees C, respectively. Maximal number of binding sites in rat brain membranes were found to be 94 and 81 fmol/mg of protein at 25 and 37 degrees C, respectively. (3H)CTOP binding over a concentration range of 0.1 to 10 nM was best fit by a one site model consistent with binding to a single site. The general effect of different metal ions and guanyl-5'-yl-imidodiphosphate on (3H)CTOP binding was to reduce its affinity. High concentrations (100 mM) of sodium also produced a reduction of the apparent mu receptor density. Utilizing the delta opioid receptor specific peptide (3H)-(D-Pen2,D-Pen5)enkephalin, CTOP appeared to be about 2000-fold more specific for mu vs. delta opioid receptor than naloxone. Specific (3H)CTOP binding was inhibited by a large number of opioid or opiate ligands.
Research Organization:
Univ. of Arizona Health Sciences Center, Tucson (USA)
OSTI ID:
6470418
Journal Information:
J. Pharmacol. Exp. Ther.; (United States), Journal Name: J. Pharmacol. Exp. Ther.; (United States) Vol. 248:1; ISSN JPETA
Country of Publication:
United States
Language:
English

Similar Records

(D-Pen2,4 prime -125I-Phe4,D-Pen5)enkephalin: A selective high affinity radioligand for delta opioid receptors with exceptional specific activity
Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Journal of Pharmacology and Experimental Therapeutics; (United States) · OSTI ID:6144464
Opioid binding sites in the guinea pig and rat kidney: Radioligand homogenate binding and autoradiography
Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Molecular Pharmacology; (United States) · OSTI ID:5463829
Quantitative analysis of multiple kappa-opioid receptors by selective and nonselective ligand binding in guinea pig spinal cord: Resolution of high and low affinity states of the kappa 2 receptors by a computerized model-fitting technique
Journal Article · Tue May 01 00:00:00 EDT 1990 · Molecular Pharmacology; (USA) · OSTI ID:6749572

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METALS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
DRUGS
ELEMENTS
ENDORPHINS
ENKEPHALINS
IN VITRO
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
METALS
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
POLYPEPTIDES
PROTEINS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SODIUM
SOMATOSTATIN
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES