OXIDATIVE STRESS-RESPONSE IN YEAST - PURIFICATION AND CHARACTERIZATION OF GLUTATHIONE-REDUCTASE FROM HANSENULA-MRAKII

Glutathione reductase was purified from a yeast, Hansenula mrakii IFO 0895, to approximately 3500-fold with 59% activity yield. The enzyme w as homogenous on polyacrylamide gel electrophoresis. The molecular wei ght of the enzyme was estimated to be 56 kDa by SDS polyacrylamide gel electrophoresis, and 123kDa by gel filtration using a calibrated Seph adex G-150 column. The K-m values for glutathione disulfide and NADPH were 21.3 mu M and 14.3 mu M, respectively. The enzyme was most active at pH 7.5, 55 degrees C. The enzyme was stable up to 40 degrees C, an d between pHs 4 and 10. The enzyme was inhibited by p-chloromercuriben zoate and metal ions such as Fe3+, Cd2+, CU2+, and Zn2+.