Small-molecule inhibitor: Z-DEVD-FMK

Name

History: The selectivity of caspase-3 for Asp-Glu-Val-Asp was discovered by Nicholson et al. (1995), and z-DEVD-fmk was developed as a cell-permeant, irreversible inhibitor by Enzyme System Products (Dublin, CA) about 1997.
Peptidases inhibited: z-DEVD-fmk is commonly regarded as highly selective for caspase-3. Cryns & Yuan (1998) point out that caspase-2 and caspase-7share the preference for Asp in the P4 position, and they are also susceptible to inhibition by z-DEVD-fmk. Caspase-8 also has been reported to be inhibited (Medema et al., 1997).
Mechanism: Inhibition is irreversible.

Structure
Chemical/biochemical name: N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp-(OMe)-fluoromethylketone
Related inhibitors: The "DEVD" tetrapeptide has been used also in an aldehyde inhibitor (Ac-Asp-Glu-Val-Asp-H), but in that the three carboxyl groups were not esterified.

Inhibitor class: This compound is of the halomethylketone class of cysteine peptidase inhibitors. Both chloro- and fluoromethylketones inhibit cysteine peptidases, and the fluoromethylketones are generally specific for cysteine peptidases. These compounds are activated ketones that form tetrahedral adducts at the active site, and may go on to react covalently, forming thioethers with the active site cysteine. The halomethylketones have been reviewed by Powers et al. (2002), pp. 4646 - 4656, and Yin et al. (2006).
Comment: z-DEVD-fmk is one of the inhibitors that can distinguish the activity of one caspase from that of another. The tri-esterified molecule is presumably a pro-inhibitor, and the three methyl ester groups are likely to be removed by esterases in vivo so as to generate a complex mixture of functional inhibitor molecules.