Characterization of rat brain opioid receptors by [Tyr-3,5-3H]1,d-Ala2, Leu5-enkephalin binding
| Autor: | Katalin Di Gleria, Mária Szücs, Sándor Benyhe, Judit Kevei, Helga Süli-Vargha, K. Medzihradszky, Judit Szécsi, Anna Borsodi, Géza Tóth |
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| Rok vydání: | 1985 |
| Předmět: |
Enkephalin
Stereochemistry medicine.drug_class Enkephalin Methionine Neuropeptide Tritium Binding Competitive Biochemistry Cellular and Molecular Neuroscience Opioid receptor medicine Animals Endorphins Binding site Receptor Opioid peptide Binding Sites Chemistry Ligand Cell Membrane Brain Enkephalins General Medicine Rats Kinetics Receptors Opioid |
| Zdroj: | Neurochemical Research. 10:627-635 |
| ISSN: | 1573-6903 0364-3190 |
| Popis: | [Tyr-3,5-3H]1, D-Ala2, Leu5-enkephalin [( 3H]DALA) was used for labeling the opioid receptors of rat brain plasma membranes. The labeled ligand was prepared from [Tyr-3,5-diiodo]1, D-Ala2, Leu5-enkephalin by catalytic reductive dehalogenation in the presence of Pd catalyst. The resulting [Tyr-3,5-3H]1, D-Ala2, Leu5-enkephalin had a specific activity of 37.3 Ci/mmol. In the binding experiments steady-state level was reached at 24 degrees C within 45 min. The pseudo first order association rate constant was 0.1 min-1. The dissociation of the receptor-ligand complex was biphasic with k-1-s of 0.009 and 0.025 min-1. The existence of two binding sites was proved by equilibrium studies. The high affinity site showed a KD = 0.7 nM and Bmax = 60 fmol/mg protein; the low affinity site had a KD = 5 nM and Bmax = 160 fmol/mg protein. A series of opioid peptides inhibited [3H]DALA binding more efficiently than morphine-like drugs suggesting that labeled ligand binds preferentially to the delta subtype of opioid receptors. Modification of the original peptides either at the C or N terminal ends of the molecules resulted in a decrease in their affinity. |
| Databáze: | OpenAIRE |
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