NADPH - PHENANTHRENEQUINONE NONE OXIDOREDUCTASE IN CHANNEL CATFISH (ICTALURUS-PUNCTATUS)

The toxicity of certain polycyclic aromatic hydrocarbons has been rela ted to the phenomenon of oxidative stress. Recent studies in our labor atory have demonstrated that 9,10-phenanthrenequinone (RQ) is an effic ient redox cycling agent in cytosols of several organs of the channel catfish (Ictalurus punctatus). Stomach cytosol demonstrated a high lev el of dicoumarol-sensitive PQ reduction which was at least tenfold gre ater than that seen in kidney, liver or gill. In the presence of stoma ch cytosol, Pe stimulated production of superoxide anion in-vitro at r ates several fold higher than did menadione, a model redox active quin one. The active component from stomach cytosol has been purified, and is termed NADPH. phenanthrenequinone oxidoreductase, which the authors believe represents a novel quinone-reducing enzyme in this species.