Slow Isomerization Step in the Interaction Between Mouse Dopamine Transporter and Dopamine Re-uptake Inhibitor N-(3-iodoprop-2e-enyl)-2beta-carbo-[3h]methoxy-3beta-(4'-methylphenyl)nortropane.
From: Institute of Organic and Bioorganic Chemistry, University of Tartu, 2 Jakobi Str, 51014 Tartu, Estonia.
Neuroscience letters
- Publish Date: Dec 2006
- ISSN: 0304-3940
- Volume: 410
- Issue: 3
- Pages: 218-21
- Medium: Print
- Language: English
- Citation (JAMA): Stepanov Vladimir, Järv Jaak, et al. Slow Isomerization Step in the Interaction Between Mouse Dopamine Transporter and Dopamine Re-uptake Inhibitor N-(3-iodoprop-2e-enyl)-2beta-carbo-[3h]methoxy-3beta-(4'-methylphenyl)nortropane.. Neurosci. Lett. Dec 2006;410:218-21
Abstract
The kinetics of the association and dissociation of the tritium-labeled selective and potent dopamine transporter inhibitor N-(3-iodoprop-2E-enyl)-2beta-carbo-[3H]methoxy-3beta-(4’-methylphenyl)nortropane ([3H]PE2I) with the transporter of mouse striatal membranes was studied. The analysis revealed that the specific binding of [3H]PE2I occurs within a homogeneous population of binding sites in these membranes. The relatively slow binding process was characterized by the pseudo-first-order rate constant kobs. The plot of these rate constants versus free radioligand concentration was hyperbolic, demonstrating that at least two kinetically distinguishable steps can be identified in the interaction of dopamine transporter with this inhibitor. The fast and reversible binding step, characterized by dissociation constant KA = 51 +/- 23 nM, is followed by a slow but also reversible isomerization step of the complex, characterized by the isomerization rate constant ki = (7 +/- 2)10(-2) s(-1) and by the rate constant k(-i) = (3.9 +/- 0.5)10(-3) s(-1) for the reverse process. This isomerization step increases the apparent affinity of the ligand and probably consists of a conformational transition of the transporter protein, induced by the inhibitor molecule.
Mesh Headings (Keywords): Animals, Corpus Striatum, Dopamine Plasma Membrane Transport Proteins, Dopamine Uptake Inhibitors, Dose-Response Relationship, Drug, Drug Interactions, Male, Mice, Nortropanes, Protein Binding, Tritium
Check for Full Text / PubMed Unique Identifier (PMID): 17074440
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