Expression of a cDNA Encoding Rat Liver DT-Diaphorase in Escherichia Coli
Quinones and their precursors are widely distributed in nature, both as natural compounds and as environmental pollutants (Smith,1985). The toxicity and mutagenicity of quinones are believed to be due to their enzymatic one electron reduction by flavoenzymes to form semiquinones which can alkylates critical nucleophiles or generate superoxide anion radical through a redox cycling process (Thor et al., 1985; Chesis et al., 1984). DT-diaphorase (NAD(P)H: quinone oxidoreductase, EC 220.127.116.11.) is a unique flavoprotein in that it catalyzes the obligatory two electron reduction of quinones to hydroquinones via a pathway bypassing the formation of semiquinone; thus, playing a protective role against quinone toxicity (Ernster et al., 1986; Atallah et al., 1988).
KeywordsCell Free Extract HindIII Site Quinone Oxidoreductase Quinone Reductase Electron Reduction
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- Ernster, L., Estabrook, R.W., Hochstein, P. and Orrenius, S., eds. (1987). In, DTdiaphorase a quinone reductase with special functions in cell metabolism and detoxication. Chem. Scripta 27A.Google Scholar
- Robertson, J.A., Chen, H. and Nebert, D.W. (1986). NAD(P)H: Menadione oxidoreductase, novel purification of enzyme, cDNA and complete amino acid sequence, and gene regulation. J. Biot. Chem. 261, 15794–15799.Google Scholar
- Thor, H., Smith, M.T., Hartzell, P., Bellomo, G., Jewell, S.A. and Orrenius, S. (1985). The metabolism of menadione (2-methyl-1,4-naphthoquinone) by isolated hepatocytes: a study of the implications of oxidative stress in intact cells. J. Biol. Chem. 257, 12419–12424.Google Scholar
- Williams, J.B., Lu, A.Y.H., Cameron, R.G. and Pickitt, C.B. (1986). Rat liver NAD(P)H: quinone reductase, construction of a quinone reductase cDNA clone and regulation of quinone reductase mRNA by 3-methylcholanthrene and in persistent hepatocyte nodules induced by chemical carcinogens. J. Biol. Chem. 261, 5524.PubMedGoogle Scholar