Table 1

Inhibition of proteasome catalytic activitiesa

Compoundkassociation = kobserved/[I] (m−1 · s−1)
Chymotrypsin-like activityPGPH activityTrypsin-like activity
Dihydroeponemycin66.4 ± 8.9 (20–60)60.5 ± 8.8 (12.5–50)4.4 ± 0.43 (125–500)
Lactacystin675 ± 86.1 (1.0–2.25)3.71 ± 0.48 (60–100)29.9 ± 4.21 (50–100)
NLVS9820 ± 3810 (0.2–0.4)4.95 ± 1.65 (60–100)0 (75–100)
  • a The rates of covalent inhibition (kassociations) of the three major proteasome catalytic activities were determined for the eponemycin analogue dihydroeponemycin as well as the potent inhibitors lactacystin and the peptide vinyl sulfone NLVS. Ranges of concentrations (given in parentheses in μm) were used to determine the kassociation for inhibition of individual enzymatic activities.