FIGURE 8.

Effects of oxidized Rpn1 and Rpn2 on 20 S activity. Representative trace (A) and mean of AMC fluorescence (B) showing 20 S chymotrypsin-like activity measured in the presence or absence of Rpn1/Rpn2 (0.5 μg; 1:1 ratio) for 15 min and then for an additional 10 min after addition of H₂O₂ and GSH to the cultures. C, mean rates of 20 S proteasome chymotrypsin-like activity in the presence or absence of Rpn1, Rpn2, or both Rpn1 and Rpn2. D, 20 S CP (0.5 μg) was incubated for 10 min with or without unoxidized Rpn1 (0.5 μg), Rpn2 (0.5 μg), or Rpn1/Rpn2 (1:1 ratio) or oxidized Rpn1, Rpn2, or Rpn1/Rpn2 that had been pre-treated with GSH (100 μm) and H₂O₂ (200 μm). Chymotrypsin-like activity was then measured using AMC fluorogenic substrate. Means ± S.D. are shown. Each experiment was repeated in triplicate. *, p < 0.05 or **, p < 0.01.