NONPHOSPHORYLATING RESPIRATION AS A MECHANISM MINIMIZING FORMATION OFREACTIVE OXYGEN SPECIES IN THE CELL

It is generally believed that the cell protects itself from the harmfu l side effects of aerobiosis by removing the arising superoxide (O-2(- .)) and its products. Here a concept is put forward that another intra cellular mechanism is also used for the same purpose. It is nonphospho rylating respiratory systems that are suggested to be involved in main taining safely low concentrations of both O-2 and its one-electron red uctants such as CoQ(-.). This minimizes the probability of O-2(-.) for mation. In this context, the roles of natural uncouplers (thyroid horm ones), recouplers (male sex hormones and progesterone), mitochondrial inner membrane pore, and noncoupled respiratory chain bypasses are dis cussed.