Caspase inhibitors are key research tools for studying and manipulating the process of apoptosis. Q-VD-OPH is a novel irreversible, broad spectrum caspase inhibitor specifically designed for in vivo research (1). Salient features include potent antiapoptotic properties (IC50 values against purified caspases are in the nanomolar range), non-toxicity and enhanced cell membrane permeability compared to FMK-based inhibitors. Q-VD-OPH is also useful for in vitro studies (1).

Fluorochrome-labeled caspase inhibitors are novel tools for detecting and quantitating caspase activation in living cells by intracellular flow cytometry, fluorescence microscopy, and 96-well fluorescence plates. These broad spectrum caspase inhibitors (FAM and SR Caspase Activity Kits) are cell permeable and are capable of binding to the active sites of caspases. A key advantage is that neither cellular fixation nor permeabilization is needed to carry out the assays (2).

SR-VAD-FMK fluorescence microscopy detection of active caspases in Jurkat cells treated with Staurosporine (1mM, 3 h).