Studies on the Damage of Structure and Function of Soybean Hypocotyl Mitochondria by Activated Oxygen
WANG Ai-Kuo, SHAO Cong-Ben, LUO Guang-Hua and GUO Jun-Yan(Kuo Chun-Yen)(South China Institute of Botany, Academia Sinica, Guangzhou 510650)LIANG Hou-Guo(Department of Biology, Lanzhou University, Lanzhou 730001)
The injury of the structure and function of soybean hypocotyl mitochondria induced by activated oxygen generated from paraquat H_2O_2 and ·OH in Fenton reaction had been studied. It was found that activated oxygen O_2~+, H_2O_2 and ·OH could induce mitochondria to swell quickly. The respiratory control ratio (RCR) and ADP: O value of mitochondria decreased markedly with an increase of paraquat concentration, thus indicating the damage of the integrity of mitochondria. Cytochrome oxidase activity was decreased by O_2~+, H_2O_2, and ·OH. Activated oxygen damaged not only the outer but also the inner membrane of mitochondria. 3 mmol/L diethyldithiocarbamate (DDC), an inhibitor of superoxide increased the damage of the mitochondria caused by paraquat. However, 5 mmol/L benzoic acid reduced the damage of the mitochondria through Fenton reaction. By analyzing lipid hydroperoxide and lipid conjugated diene, it was observed that activated oxygen O_2~+, H_2O_2 and ·OH enhanced the membrane lipid peroxidation in mitochondria. Therefore, the severe damage of the structure and function of the mitochondria caused by activated oxygen was closely relatcd to membrane lipid perexidation.