Peroxidase and Photoprotective Activities of Magnesium Protoporphyrin IX

Abstract

Magnesium-protoporphyrin IX (Mg-PPn), which is formed through chelation of protoporphyrin IX (PPn) with Mg ion by Mg chelatase, is the first intermediate for the (bacterio)chlorophyll biosynthetic pathway. Interestingly, Mg-PPn provides peroxidase activity (approximately 4 × 10(-2) units/micrometer) detoxifying H2O2 in the presence of electron donor(s). The peroxidase activity was not detected unless PPn was chelated with Mg ion. Mg-PPn was found freely diffusible through the membrane of Escherichia coli and Vibrio vulnificus, protecting the cells from H2O2. Furthermore, unlike photosensitizers such as tetracycline and PPn, Mg-PPn did not show any phototoxicity, but rather it protected cell from ultraviolet (UV)-A-induced stress. Thus, the exogenous Mg-PPn could be used as an antioxidant and a UV block to protect cells from H2O2 stress and UV-induced damage.

Exploitation of Reactive Oxygen Species by Fungi: Roles in Host-Fungus Interaction and Fungal Development

“…Several oxidative enzymes also inadvertently produce small amounts of superoxide [40]. These ROS can attack proteins, lipids, DNA, and carbohydrates in the cell, causing serious problems, including DNA mutation, lipid peroxidation, and protein oxidation [23]. Numerous studies have shown that ROS are detoxified and their levels are controlled by enzymes, including SOD, peroxidase, and catalase, in animals and plants [4,26].…”