Paraquat diaphorases in Escherichia coli.
Extracts of E. coli contain at least three easily separable NAD(P)H:paraquat diaphorases. One of these is identified as thioredoxin reductase, which accounts for most of the PQ++ diaphorase in a thioredoxin reductase overproducer but is only 25% of this activity in a wild type. NADP+, but not NAD+, inhibited the diaphorase activity of thioredoxin reductase. All of the soluble PQ++ diaphorases of E. coli are stable during fractionation by HPLC and none depend upon the cooperative action of components separable by this technique. GSSG reductase is inhibited by PQ++ and is not, to any significant degree, a contributor to the diaphorase activity of E. coli.
Liochev
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Department of Biochemistry, Duke University Medical Center, Durham, NC 27710.
Fridovich
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D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D005980:Glutathione Reductase / Q000378:metabolism; D009243:NAD / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism
D009243:NAD; D009249:NADP; D009247:NADH, NADPH Oxidoreductases; C085915:paraquat diaphorase; D005980:Glutathione Reductase; D013880:Thioredoxin-Disulfide Reductase