Paraquat toxicity and effect of hydrogen peroxide on thermophilic bacteria.
Paraquat (PQ++) increased cyanide-resistant univalent respiration in cell suspensions of five strains of obligately thermophilic bacteria. PQ++ was reduced by an NADH: or NADPH:paraquat diaphorase and selectivity for NADH, NADPH, or both electron donors varied among the thermophiles. Superoxide anion production that was dependent on the presence of PQ++ was shown by following the superoxide dismutase-inhibitable reduction of cytochrome c. In addition, the PQ++-dependent formation of hydrogen peroxide from superoxide anion was evident in two of the thermophilic strains. Catalase synthesis was induced by adding hydrogen peroxide to the growth medium of the thermophiles. The induction of catalase to eliminate hydrogen peroxide appears to be an important response of these thermophilic bacteria to oxygen toxicity.
D002374:Catalase / Q000032:analysis / Q000378:metabolism; D002478:Cells, Cultured; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D017830:Octoxynol; D010269:Paraquat / Q000494:pharmacology / Q000633:toxicity*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011190:Potassium Cyanide / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000502:physiology
D009243:NAD; D011092:Polyethylene Glycols; D009249:NADP; D017830:Octoxynol; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D011190:Potassium Cyanide; D010269:Paraquat