Abstract
Brain nitric oxide synthase (NOS), which utilizes NADPH and calcium/calmodulin as cofactors for metabolizing L-arginine to nitric oxide (NO) and L-citrulline, contains recognition sites for the flavins FAD and FMN. Using a spin-trapping technique combined with electron spin resonance spectroscopy, we report that brain NOS generates superoxide O2-. in a calcium/calmodulin-dependent manner. The "specific inhibitors" of NOS, NG-monomethyl L-arginine (L-NMMA), and NG-nitro-L-arginine methyl ester (L-NAME), have different effects on O2-. generation. For L-NMMA, O2-. production is unaffected, while for L-NAME, inhibition of this free radical is concentration-dependent.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Oxidoreductases / genetics
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Amino Acid Oxidoreductases / isolation & purification
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Amino Acid Oxidoreductases / metabolism*
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Animals
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Arginine / analogs & derivatives
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Arginine / pharmacology
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Brain / enzymology*
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Cell Line
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Chromatography, Affinity
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Electron Spin Resonance Spectroscopy / methods
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Kidney
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Kinetics
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NG-Nitroarginine Methyl Ester
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Nitric Oxide Synthase
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Superoxides / metabolism*
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Transfection
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omega-N-Methylarginine
Substances
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Recombinant Proteins
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Superoxides
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omega-N-Methylarginine
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Arginine
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Nitric Oxide Synthase
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Amino Acid Oxidoreductases
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NG-Nitroarginine Methyl Ester