Oxygen Generation and Detoxification

Figure 20.7. Mechanism of reactive oxygen species generation and detoxification.

Daub, M. E., Leisman, G. B., Clark, R. A., and Bowden, E. F. (1992). Reductive detoxification as a mechanism of fungal resistance to singlet oxygen-generating photosensitizers. Proc. Natl. Acad. Sci. USA 89 9588-9592. 

Figure 4. Scheme of interactions between active oxygen generating xenobiotics and the oxygen detoxification system. Light intensity, the rate constants of photogeneration of active oxygen, dissipation of the xenobiotics and the levels and rate constants of the enzymes interact to determine whether a plant will be spared or killed. 

The mutagenic action of rubroskyrin (785) was examined by Mori and co-workers, who revealed that this activity resulted from the generation of active oxygen in the course of detoxification. Rubroskyrin (785) becomes reduced by NADH and is autoxidized by dissolved oxygen. Then, H2O2 is produced, which immediately decomposes to reactive oxygen by a catalase. Thereafter, superoxide dismutase produces the very reactive superoxide anion. Once this process is completed, rubroskyrin is transformed to stable products that are not toxic (548). 

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