Measurements of the Antioxidant Enzyme Activities of Superoxide Dismutase, Catalase, and Glutathione Peroxidase

Abstract

Publisher Summary This chapter describes the activity assays of the major reactive oxygen species (ROS) defense system enzymes—superoxide dismutases, glutathione peroxidases (GPx), and catalase (CAT)—in cultured cells, tissue homogenates, and mammalian mitochondria. To cope with the damaging actions of ROS, organisms have evolved a sophisticated ROS defense system (RDS), consisting of low-molecular-weight antioxidants, such as glutathione, ascorbic acid, tocopherol, and uric acid, and specialized ROS-detoxifying enzymes, such as SODs, CAT, GPxs, and various thio-, peroxi-, and glutaredoxins. These enzymes represent the primary line of ROS defense. Defense enzymes can remove ROS directly or can repair the damage to other macromolecules caused by ROS. Other enzymes are involved in the renewal of the reducing power of defense enzymes. Failure of RDS to cope with the intracellular ROS production results in oxidative stress, which contributes to the damage and death of cells. Therefore, measuring the activity of RDS enzymes is a valuable diagnostic tool to determine the role of the oxidative stress in the pathology of a particular disease.