Figure 2. Specific hydrolytic activities towards fluorogenic peptide substrates of 20S and 26S proteasomes purified from different brain parts of young and aged rats.

From cerebrum, cerebellum, and hippocampus of young (white columns) and aged (black columns) rats 20S and 26S proteasomes were separated by glycerol gradient centrifugation. The proteasome containing fractions were pooled and their proteasome content determined by immunoelectrophoresis. Chymotrypsin- (chtr), trypsin- (tryp) and caspase-like (casp) proteasome activities were measured and shown as pmol substrate hydrolysis/min x µg proteasome. Values are given as means ± SEM (n = 5) and data obtained for young and aged rats were compared by Students t-test. p-values indicating statistically significant differences are indicated (*, p<0.05; **, p<0.01).