Figure 1.

Michaelis-Menten constants (K _m) of the proteasome in rat liver with age: regression plots of Michaelis-Menten constants (K _m) of the proteasome in rat liver versus age. K _m-constants were obtained from Lineweaver-Burk plots generated from proteolytic runs using four different substrate concentrations. For each concentration, triplicate samples were run. (a) Chymotrypsin-like activity: R ² of the regression line is 0.049, P = .138. (b) Trypsin-like activity: R ² = 0.417, P < .001. (c) Peptidylglutamyl peptidase activity: R ² = 0.034, P = .219. A P-value of less than  .05 was considered statistically significant.