Rapid determination of glutathione peroxidase and thioredoxin reductase activities using a 96-well microplate format : Comparison to standard cuvette-based assays

Gluthatione peroxidase and thioredoxin reductase are selenocysteine-containing enzymes that are constituents of the cellular antioxidant defense system. Conventional cuvette-based assays for glutathione peroxidase and thioredoxin reductase enzymes are laborious and time consuming. The ability to assay their activities rapidly in multiple samples would aid efforts focused on understanding the impact of these enzymes on the cellular antioxidant defense system. High throughput can be achieved with assays adapted to work in a clinical analyzer but require expensive equipment. Assays designed to work in a 96-well microplate reader provide an alternative methodology for high throughput with reduced instrumentation cost. However, due to differences in the light pathlength when using a 96-well format, the values obtained cannot be compared directly with those obtained using a 1-cm cuvette. Described here are assays for glutathione peroxidase and thioredoxin reductase modified to work in a 96-well format that inco...