The antioxidant response mechnasims of phanerochaete chrysosporium depending menadione stress factor

In order to identify the antioxidant response mechanism of Phanerochaete Chrysosporium against menadione, cells from stationary phase were treated with multiple concentration of menadione for different incubation times. Then the menadione-treated cells were investigated in terms of intracellular superoxide anion radical, hydroxyl radical and hydrogen peroxide levels, variations of SOD, CAT, G6PDH, NADH, NADPH oxidase enzyme activities, variations of energy metabolism and cell membrane peroxidation and protein oxidation levels and the results were compared with control. The highest values of hydrogen peroxide and hydroxyl radical were observed two point two-fold and one point seven-fold higher than control for menadione treated samples, respectively. The investigated antioxidant enzymes, SOD, CAT and G6PDH, gave considerable response to menadione-induced oxidative stress. The highest activities were obtained five point four-fold, five point one-fold and two point five-fold higher than control for SOD, CAT and G6PDH enzymes, respectively. In addition, NADH and NADPH oxidase enzymes that play important roles in formation of ROS were induced by menadione treatment and when compared with control the activities of these enzymes were observed four point nine-fold and fivefold higher than control. In order to decide adequacy of antioxidant system against menadione-induced oxidative stress, damages of protein and membrane lipids were investigated. The result shows that although menadione induces the formation of ROS and oxidative stress, antioxidant system is able to resist against menadione-induced oxidative stress up to relatively high concentrations of menadione. vKeywords: Menadione, Phanerochaete chrysosporium, superoxide anion radical,hydrogen peroxide, hydroxyl radical, SOD, CAT, G6PDH, NADH oxidase, NADPH oxidase, ATP, ADP,AMP, LPO, Protein carbonyl content