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  • Polymer and Materials Science  (3)
  • Radioiodinated peptides  (1)
  • [Phe1Ψ(CH2-NH)Gly2]NC(1  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Characterization of nociceptin receptors in the periphery: in vitro and in vivo studies (1999)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 160-167 
    Details
    ISSN: 1432-1912
    Keywords: Key words Nociceptin ; [Phe1Ψ(CH2-NH)Gly2]NC(1 ; 13)NH2 ; Rat and mouse vas deferens ; Guinea pig ileum and renal pelvis ; Blood pressure ; Heart rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nociceptin (NC), a series of NC fragments, naloxone as well as the pseudopeptide [Phe1Ψ(CH2-NH)Gly2]NC(1–13)NH2 ([F/G]NC(1–13)NH2) were used to characterize NC receptors in peripheral isolated organs and in vivo. Experiments on isolated organs were performed in the mouse (mVD) and rat (rVD) vas deferens (noradrenergic nerve terminals), in the guinea pig ileum (gpI; cholinergic nerves) and in the renal pelvis (gpRP; sensory nerves), and, in vivo, by measuring the blood pressure (BP) and heart rate (HR) in anaesthetised rats. NC, NCNH2 and NC(1–13)NH2 acted as full agonists with similar affinities, while shorter fragments (e.g. NC(1–12)NH2, NC(1–9)NH2, NC(1–5)NH2) were much weaker or inactive. The inhibitory effects of NC were not modified by naloxone. [F/G]NC(1–13)NH2 acted as an antagonist with similar pA 2-values (6.75 mVD, 6.83 rVD, 7.26 gpI) in the three species. In addition, it blocked NC actions in the rat in vivo. Linear Schild plots with slopes near to unity indicated that [F/G]NC(1–13)NH2 is a competitive antagonist, specific for NC receptors both in vitro (since it was inactive on opioid receptors) and in vivo (since it was inactive against carbachol). [F/G]NC(1–13)NH2 showed a residual agonistic activity in vitro (α = 0.2-0.3 in the rVD and gpI) and especially in vivo (α = 0.4 BP, 0.2 HR). These pharmacological data indicate that NC and related peptides exert their inhibitory effects in peripheral organs of various species by activating the same receptor type. Moreover, [F/G]NC(1–13)NH2 appears to be a useful tool for receptor characterization and classification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005338
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation of mono-radioiodinated tracers for study of the in vivo metabolism of atrial natriuretic peptide in humans (1995)
    Springer
    European journal of nuclear medicine 22 (1995), S. 997-1004 
    Details
    ISSN: 1619-7089
    Keywords: Atrial natriuretic peptide ; Atrial natriuretic factor ; Radioiodinated peptides ; High-performance liquid chromatography ; Kinetic study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present paper we evaluate the optimum chemical conditions for labelling atrial natriuretic peptide (ANP) and its metabolites and for preparing highly purified radiotracers which can be used for in vivo kinetic studies of ANP in humans. Synthetic a h1–28ANP and some hormone metabolites were iodinated with Na125I or Na131I by means of the lactoperoxidase (ANP) or the chloramine-T (ANP metabolites) technique. The biological activity of labelled ANP was tested by means of a binding study using mouse cardiac membranes. A high-performance liquid chromatography (HPLC) procedure was used to purify the labelled hormone and the principal labelled metabolites in venous plasma samples collected up to 50 min after the injection of125I-labelled ANP from nine healthy men. The main ANP kinetic parameters were derived from the disappearance curves of the [125I]ANP, which were satisfactorily fitted by a biexponential function in all subjects. The main advantages of this tracer technique are: (1) high accuracy, allowing the identification of the metabolites produced in vivo under steady-state conditions after injection of the precursor (labelled hormone); (2) high sensitivity, allowing the detection of minimal quantities of metabolites (that cannot be identified on the basis of the integrated areas from the ultraviolet-absorbing peaks on HPLC); (3) high specificity, allowing the detection of possible in vitro artefactual generation of cleavage products of ANP using an internal labelled standard. Utilizing this tracer method, it was possible to estimate the principal parameters of ANP kinetics and also to plot the appearance curves of the labelled metabolites produced in vivo after the injection of the labelled precursor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808410
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  • 3
    Electronic Resource
    Electronic Resource
    Conformational analysis of an opioid peptide in solvent media that mimic cytoplasm viscosity (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 367-372 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many neuropeptides exert their action between the presynaptic vesicles and postsynaptic transmembrane receptors, crossing different layers of specialized cytoplasm. Biomimetic media usually employed to study bioactive peptides do not reproduce the physico chemical environment of cytoplasm - in particular, the high viscosity of this biological fluid. Here we describe a Conformational study of a δ-selective opioid peptide, deltorphin I, at variable temperatures in several biocompatible media characterized by varying values of viscosity and dielectric constant. It was found that only viscosity, among these parameters, induces ordered conformations; that is, it acts as a Conformational sieve. This finding suggests that the high viscosity of the intersynaptic fluid contributes, in addition to the membrane catalysis proposed by Schwyzer, in overcoming the so-called entropic barrier to the transition state of peptide-receptor interaction by selecting ordered conformations prior to receptor interaction.The folded conformer found in the 80 : 20 (v : v) DMSOd6/H2O cryoprotective mixture at 265 K has a shape consistent with those of rigid nonpeptidic opiates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320412
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Nmr studies of a series of dehydrodermorphins (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 129-138 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The third and fifth aromatic residues of dermorphin, a potent μ-opioid peptide, and of its N-terminal fragments, from the pentapeptide to the parent heptapeptide amide, have been systematically substituted with Z-dehydrophenylalanine (Δ-Phe) and/or Phe to investigate the conformation-activity relationship.The characterization in DMSO-d6 at 500 MHz indicates that, in this solvent, all peptides adopt essentially random, extended conformations, as a consequence of the strong solvation. The chemical shift of the methyl group of D-Ala is influenced by the precise orientation of the side chain of the third residue in a fashion that can be correlated to the μ potency, consistently with our model of μ-receptor.However, the complexes of the pentapeptides with 18-crown-6-ether, when dissolved in chloroform, adopt ordered, folded conformations, a behavior that closely parallels the CD observations in methanol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360280115
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  • 5
    Electronic Resource
    Electronic Resource
    Succinimide-mediated pathway for peptide bond cleavage: Kinetic study on an Asn-Sar containing peptide (1996)
    New York : Wiley-Blackwell
    Biopolymers 40 (1996), S. 543-551 
    Details
    ISSN: 0006-3525
    Keywords: peptide bond cleavage ; asparagine deamidation ; succinimide ring formation ; kinetics and mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cleavage reaction of the peptide bond next to the Asn residue has been studied in the pH range 7.4-13.8 at 37°C and μ = 1M. This reaction yields an N-terminal peptide fragment having at its C-terminus a succinimide ring, which rapidly hydrolyses to both asparagine and iso-asparagine residues.For both the two consecutive reactions, peptide bond cleavage and the succinimide hydrolysis, the general trend is an increase of the reaction rate with the pH. However, for the hydrolysis reaction there is a small decrease in the pH range 10-11 caused by the deprotonation of the succinimide nitrogen atom. Kinetic evidence indicates that the cleavage reaction is a multistep process with a change in the rate-determining step at pH 8.5-9.0. The mechanism involves preequilibrium deprotonation of the NH2 amide group of the Asn side chain, followed by nucleophilic attack of the nitrogen atom on the carbonyl carbon atom of the same asparagine residue, giving a cyclic intermediate. Then, general acid-catalyzed departure of the leaving group gives the final reaction product. At pH 〈 8.5, the formation of the cyclic intermediate is rate determining, whereas, at higher pH, it is the departure of the leaving group. © 1997 John Wiley & Sons, Inc. Biopoly 40: 543-551, 1996
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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