Abstract
Caspases have an active site cysteine whose oxidation blocks catalytic activity. Caspase activity, measured in lysates of apoptotic cells, was inhibited by H2O2 with an IC50 of 7 μM. Recombinant caspase-3 was directly inhibited by H2O2, with an estimated second-order rate constant of 750 M-1 s-1. These values were determined when H2O2 was added while the caspases were cleaving a peptide substrate. There was a 40-fold decrease in sensitivity to inactivation if the substrate was absent at the time of H2O2 addition. These results rationalise conflicting reports of the sensitivity of caspase-3 to H2O2, and identify a novel mechanism for sensitising a thiol enzyme to oxidative inactivation.
| Original language | English |
|---|---|
| Pages (from-to) | 229-232 |
| Number of pages | 4 |
| Journal | FEBS Letters |
| Volume | 517 |
| Issue number | 1-3 |
| DOIs | |
| State | Published - 24 Apr 2002 |
| Externally published | Yes |
Keywords
- Apoptosis
- Caspase
- Cysteine
- Hydrogen peroxide
- Oxidation
- Thiol