Superoxide Dismutase and Catalase
Superoxide dismutase catalyzes the dismutation of superoxide to H2O2, which is further reduced to water by catalase or peroxidase. Two types of SOD are isolated from mammalian tissues: (1) copper-zinc SOD (CuZnSOD), the cytoplasmic enzyme, which is inhibited by cyanide; and (2) manganese SOD (MnSOD), the mitochondrial enzyme, which is not inhibited by cyanide. SOD activity and polymorphisms have been implicated in AMD in certain populations.
Catalase catalyzes the reduction of H2O2 to water. At present, information on catalase activity in the retina is limited. Total retinal catalase activity has been found to be very low but detectable in rabbits. A protective role for catalase has been reported in rats with retinal ischemia–reperfusion injury, where it prevented RGC loss and preserved function as shown by electroretinography. In addition, treatment with catalase was shown to be protective against hyperglycemia-induced oxidative stress in cell culture and animal models.
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Chen B, Tang L. Protective effects of catalase on retinal ischemia/reperfusion injury in rats. Exp Eye Res. 2011;93(5):599–606.
Kowalski M, Bielecka-Kowalska A, Oszajca K, et al. Manganese superoxide dismutase (MnSOD) gene (Ala-9Val, Ile58Thr) polymorphism in patients with age-related macular degeneration (AMD). Med Sci Monit. 2010;16(4):CR190–196.
Ohta Y, Yamasaki T, Niwa T, Niimi K, Majima I, Ishiguro I. Role of catalase in retinal antioxidant defence system: its comparative study among rabbits, guinea pigs, and rats. Ophthalmic Res. 1996;28(6):336–642.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.