TABLE 3.
Interaction of PI-9 and the PI-9 Asp mutant with recombinant caspasesa
| Caspase type | % Inhibition of enzyme activity
|
||||
|---|---|---|---|---|---|
| PI-9 | PI9E340D | CrmA | DEVD-cho | YVAD-cmk | |
| ICE-like | |||||
| Caspase-1 | 30 | 65 | 100 | NDb | 95 |
| Caspase-4 | 70 | 5 | 40 | ND | 0 |
| Caspase-5 | 30 | 50 | 5 | ND | 10 |
| Effectors | |||||
| Caspase-2 | 5 | 25 | 0 | ND | ND |
| Caspase-3 | 10 | 10 | 5 | 100 | ND |
| Caspase-6 | 10 | 70 | 8 | 100 | ND |
| Caspase-7 | 10 | 60 | 8 | 100 | ND |
| Activators | |||||
| Caspase-8 | 10 | 82 | ND | 95 | ND |
| Caspase-10 | 35 | 90 | ND | 95 | ND |
a
Recombinant caspases (approximately 4 nM) were incubated with 20 nM PI-9, PI9E340D, or CrmA. The peptide inhibitors were used at 50 μM. Residual enzyme activity was measured and compared to that in an uninhibited reaction. The ICE-like caspases were assayed with the fluorescent substrate z-YVAD-AFC, and the effector and activator caspases were assayed with the fluorescent substrate z-DEVD-AFC (both from Enzyme Systems Products).
b
ND, not determined.