Singlet oxygen production by biological systems.

Singlet oxygen (1 delta g) is a highly reactive, short-lived intermediate which readily oxidizes a variety of biological molecules. The biochemical production of singlet oxygen has been proposed to contribute to the destructive effects seen in a number of biological processes. Several model biochemical systems have been shown to produce singlet oxygen. These systems include the peroxidase-catalyzed oxidations of halide ions, the peroxidase-catalyzed oxidations of indole-3-acetic acid, the lipoxygenase-catalyzed oxidation of unsaturated long chain fatty acids and the bleomycin-catalyzed decomposition of hydroperoxides. Results from these model systems should not be uncritically extrapolated to living systems. Recently, however, an intact cell, the human eosinophil, was shown to generate detectable amounts of singlet oxygen. This result suggests that singlet oxygen may be shown to be a significant biochemical intermediate in a few biological processes.