BYK191023 (2-[2-(4-Methoxy-pyridin-2-yl)-ethyl]-3H-imidazo[4,5-b]pyridine) Is an NADPH- and Time-Dependent Irreversible Inhibitor of Inducible Nitric-Oxide Synthase
| العنوان: | BYK191023 (2-[2-(4-Methoxy-pyridin-2-yl)-ethyl]-3H-imidazo[4,5-b]pyridine) Is an NADPH- and Time-Dependent Irreversible Inhibitor of Inducible Nitric-Oxide Synthase |
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| المؤلفون: | Mauro Tiso, Rainer Boer, Claire Kenney, Christian Hesslinger, Andreas Strub, Dennis J. Stuehr |
| المصدر: | Molecular Pharmacology. 73:1244-1253 |
| بيانات النشر: | American Society for Pharmacology & Experimental Therapeutics (ASPET), 2008. |
| سنة النشر: | 2008 |
| مصطلحات موضوعية: | Imidazopyridine, Time Factors, Pyridines, Stereochemistry, Iron, Metabolite, Size-exclusion chromatography, Nitric Oxide Synthase Type II, Heme, Nitric Oxide, Tritium, Cell Line, Mice, chemistry.chemical_compound, Animals, Humans, Anaerobiosis, Enzyme Inhibitors, Chromatography, High Pressure Liquid, Pharmacology, chemistry.chemical_classification, Carbon Monoxide, biology, ATP synthase, Imidazoles, Cytochrome P450, Enzyme Activation, Oxygen, Nitric oxide synthase, Kinetics, Enzyme, chemistry, Biochemistry, Chromatography, Gel, biology.protein, Molecular Medicine, Dimerization, Oxidation-Reduction, NADP |
| الوصف: | Imidazopyridine derivates were recently shown to be a novel class of selective and arginine-competitive inhibitors of inducible nitric-oxide synthase (iNOS), and 2-[2-(4-methoxypyridin-2-yl)-ethyl]-3H-imidazo[4,5-b]pyridine (BYK191023) was found to have very high selectivity in enzymatic and cellular models ( Mol Pharmacol 69: 328-337, 2006 ). Here, we show that BYK191023 irreversibly inactivates murine iNOS in an NADPH- and time-dependent manner, whereas it acts only as a reversible l-arginine-competitive inhibitor in the absence of NADPH or during anaerobic preincubation. Time-dependent irreversible inhibition by BYK191023 could also be demonstrated in intact cells using the RAW macrophage or iNOS-overexpressing human embryonic kidney 293 cell lines. The mechanism of BYK191023 inhibition in the presence of NADPH was studied using spectral, kinetic, chromatographic, and radioligand binding methods. BYK191023-bound iNOS was spectrally indistinguishable from l-arginine-bound iNOS, pointing to an interaction of BYK191023 with the catalytic center of the enzyme. [(3)H]BYK191023 was recovered quantitatively from irreversibly inactivated iNOS, and no inhibitor metabolite was detected by high-performance liquid chromatography (HPLC). Size exclusion chromatography revealed only about 20% iNOS dissociation into monomers. Furthermore, HPLC and spectrophotometric analysis showed that the irreversible inhibition was associated with loss of heme from iNOS and a reduced ability to form the distinctive ferrous heme-CO complex (cytochrome P450). Thus, enzyme inactivation is mainly caused by heme loss, and it occurs in the inhibitor-bound enzyme in the presence of electron flux from NADPH. |
| تدمد: | 1521-0111 0026-895X |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7a36fa0ec5312ab8270687edb40faf41Test https://doi.org/10.1124/mol.107.041319Test |
| رقم الانضمام: | edsair.doi.dedup.....7a36fa0ec5312ab8270687edb40faf41 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15210111 0026895X |
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