Journal
FEBS LETTERS
Volume 517, Issue 1-3, Pages 229-232Publisher
WILEY
DOI: 10.1016/S0014-5793(02)02629-7
Keywords
thiol; cysteine; hydrogen peroxide; oxidation; caspase; apoptosis
Funding
- NIGMS NIH HHS [GM48614, GM54176] Funding Source: Medline
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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 muM. 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. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
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