On the Mechanism of Oxygen Activation in Chemical and Biological Systems

It is shown that activation of oxygen in model chemical and biological systems associated with the formation of superoxide anion radicals ( O_2^ - ) leads to a decrease in the content of molecular oxygen in the buffer. The following chemical and enzymatic reactions were considered: autooxidation of adrenaline in an alkaline medium, phenazine methosulfate/NADH, as well as the xanthine–xanthine oxidase reaction. It was found that when the chemical transformation of the substrate occurs in each of these reactions O 2 is consumed from the buffer, leading to temporary hypoxic conditions. Nitro blue tetrazolium and superoxide dismutase were used to determine the production of anion radicals O_2^ - . It was discovered for the first time that O_2^ - is produced in the glucose–glucose oxidase reaction, which is known as a reaction that does not generate superoxide. Catalase in reactions reacted with hydrogen peroxide, the product of O_2^ - disproportionation, and molecular oxygen was detected under study buffer. Thus, the following oxygen conversions in the studied reactions are shown: О 2 → O_2^ - → Н 2 О 2 → О 2 . They may also occur in intracellular systems with the involvement of appropriate oxidoreductases and antioxidant enzymes.