A STUDY ON THE SUPEROXIDE DISMUTASE OF SOYBEAN SEEDS
Wang Ai-guo, Luo Guang-hua, Shao Cong-ben, Wu Shu-jun and Guo Jun-yan (Kuo Chun-yen) (South China Institute of Botany, Academia Sinica)
Superoxide dismutase (SOD) of soybean seeds inhibited the autooxidation of epinphrine and the photochemical reduction of nitrio blue tetrazolium (NBT). The inhibition of the latter reacticn was used as a measure of determining SOD activity the quantitatively. The SOD activity of soybean seeds was found to be inhibited by potassium cyanide, but was not affected by chloroform-ethanol which indicating that the SOD in soyboan seeds was of Cu-Zn type. Soybean SOD was relatively heat-stable, its enzymic activity was lost when kept at 70℃ for 5 min. When the crude extract of soybean SOD was passed through polyacrylamide gel during electrophoresis and stained for enzymic activity with NBT, it was shown to contain five or six distinguishable transparent isoenz yme bands on a blue background. When the crude neutral extract of soybean SOD was purified with chloroformethanol and (NH_4)_2 SO_4 and then chromatographed on Sephadex G-100, the specific activity was shown to increase 13-fold. The purified soybean SOD had the same optical absorption spectra as the bovine blood SOD.