Generation of superoxide by purified brain nitric oxide synthase.
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.
D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000201:enzymology*; D002460:Cell Line; D002846:Chromatography, Affinity; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D007668:Kidney; D007700:Kinetics; D019331:NG-Nitroarginine Methyl Ester; D019001:Nitric Oxide Synthase; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014162:Transfection; D019323:omega-N-Methylarginine
D011994:Recombinant Proteins; D013481:Superoxides; D019323:omega-N-Methylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester