Production of OH-radical-type oxidant by lucigenin.
In the presence of NADH- reductases (dihydrolipoamide: NAD oxidoreductase E. C.1.8.1.4 from pig heart or from Clostridium kluyveri; frequently also addressed as "diaphorases") and NADH lucigenin strongly increases ethylene production from a-keto-methylthiobutyrate (KMB) as an indicator for strong oxidants of the OH-radical type. These reactions are further stimulated in the presence of Fe3+ ions. With these NADH-"diaphorases", the structurally similar poison, paraquat, in the absence or presence of Fe3+ has no effect. With ferredoxin-NADP reductase (E. C.1.18.1.2.), however, paraquat reacts quasi identical to lucigenin. Superoxide dismutase, catalase, free radical- or OH-scavengers such as mannitol, propylgallate, DABCO, and desferal inhibit the reaction whereas EDTA (in the presence or absence of added Fe3+) is stimulatory. From these data we conclude that the superoxide--indicator LUC is redox-active after unspecific coupling to several almost ubiquitory NAD(P)H- reductases catalyzing monovalent oxygen reduction. Lucigenin thus should no longer be used as a "specific" superoxide indicator. This report is in agreement with very recent results by Liochev and Fridovich (Arch. Biochem. Biophys. 337, 115 [1997]) and Vasquez-Vivar et al. (FEBS Lett. 403, 127 (1997).
Heiser
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Technische Universität München, Lehrstuhl für Phytopathologie, Freising-Weihenstephan, Germany.
Muhr
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A
Elstner
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EF
D000166:Acridines / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D003013:Clostridium / Q000201:enzymology; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D005030:Ethylenes / Q000096:biosynthesis*; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism*; D008715:Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology; D016877:Oxidants / Q000378:metabolism*; D013552:Swine
D000166:Acridines; D005030:Ethylenes; D016877:Oxidants; C033472:10,10'-dimethyl-9,9'-biacridinium; D017665:Hydroxyl Radical; C014632:2-keto-4-methylthiobutyric acid; C036216:ethylene; D008715:Methionine; D005287:Ferredoxin-NADP Reductase; D008058:Dihydrolipoamide Dehydrogenase