Conversion of 4-nitroquinoline 1-oxide (4NQO) to 4-hydroxyaminoquinoline 1-oxide by a dicumarol-resistant hepatic 4NQO nitroreductase in rats and mice.
The product formed from 4-nitroquinoline 1-oxide (4NQO), a potent carcinogen, by the action of mouse NADH:4NQO nitroreductase NR-1 was directly identified as 4-hydroxyaminoquinoline 1-oxide (4HAQO) by high performance liquid chromatography analyses in two systems. In liver cytosols from both male and female mice, NADH:4NQO nitroreductase was the predominant enzyme catalyzing the reduction of 4NQO. Rat liver cytosol catalyzed the conversion of 4NQO to either 4HAQO or a glutathione conjugate depending upon coenzyme or cosubstrate availability. Whereas NAD(P)H:quinone reductase (NAD(P)H:(quinone acceptor) oxidoreductase; DT diaphorase; EC 1.6.99.2) was the predominant 4NQO reductase present in liver cytosol from Sprague-Dawley rats, dicumarol-resistant NADH:4NQO nitroreductase specific activities were comparable with those of mouse liver cytosols. A 4NQO nitroreductase from rat liver cytosol was separated from NAD(P)H:quinone reductase chromatographically and shown to have a strong preference for NADH and to be insensitive to inhibition by dicumarol.
Benson
A M
AM
Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock 72205-7199.
D015108:4-Hydroxyaminoquinoline-1-oxide / Q000378:metabolism*; D015112:4-Nitroquinoline-1-oxide / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000201:enzymology; D005260:Female; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D015108:4-Hydroxyaminoquinoline-1-oxide; D009249:NADP; D015112:4-Nitroquinoline-1-oxide; D009247:NADH, NADPH Oxidoreductases; C021877:nitroquinoline N-oxide reductase