During the normal course of metabolism, oxygen is partly reduced as electrons leak out of the electron transport chain during respiration. These partially reduced oxygen species (ROS) can react with organic substances through non-catalytic means. Furthermore, ROS can be generated via endogenous enzyme systems like plasma NADPH oxidase, cytoplasmic xanthine oxidase and organelle sources e.g., cytochrome P-450. ROS have been implicated in regulating diverse cellular functions including proliferation, defense against pathogens, intra-cellular signaling, transcriptional activation and apoptosis. Elevation of ROS beyond the buffering capacity of the cell can lead to oxidative stress. Elevated ROS levels can lead to damage of DNA/RNA, proteins and lipids which may lead to apoptosis. Cells have developed several mechanisms to counter act elevated ROS levels such as a thiol reducing buffer composed of cellular thiol levels (glutathione and thioredoxion) for the maintenance of the reduction-oxidation (redox) state of the cell, and enzymes to remove ROS (catalase, superoxide dismutase and glutathione peroxidase) (1-2).

Figure 1. Detection of glutathione (GSH) utilizing the Fluoro Thiol kit.

Figure 2. Jurkat cells were incubated with 1 mM staurosporine (4) for 3 hours. After which thiol levels were quantified using Cell Technology’s Fluoro Thiol kit. The graph represents approximately 1 x 10 4 cells per reaction (n=3).