Table 1. Kinetic comparison of homodimeric caspase-8 and heterodimeric caspase-8/FLIPL.
Values for enzyme concentration were obtained using active-site-titrated enzymes, as described in the Experimental section.
| Enzyme | Sodium citrate | [Enzyme] (nM) | Km (μM) | kcat (s−1) | 10−4×kcat/Km (M−1·s−1) |
|---|---|---|---|---|---|
| Cleaved caspase-8 | − | 58.0 | 55.2±2.0 | 0.65±0.1 | 1.2±0.2 |
| Cleaved caspase-8 | + | 29.0 | 20.6±0.3 | 1.25±0.2 | 6.1±1.1 |
| Non-cleavable caspase-8 | + | 50.0* | No measurable activity | ||
| Non-cleavable caspase-8+1 μM FLIP | + | 20.9 | 31.3±0.6 | 0.98±0.1 | 3.1±0.4 |
| Non-cleavable caspase-8+1 μM FLIP D297A | + | 20.9 | 29.3±0.7 | 0.78±0.1 | 2.7±0.4 |
* Enzyme activity was too low to measure, so the value represents total protein.