Fluorometric detection of active cellular caspase 1 using cell-permeable, non-toxic fluorochrome inhibitor of caspase 1 FAM-YVAD-FMK, which is carboxyfluorescein (FAM) derivative of valylalanylaspartic acid (VAD) fluoromethyl ketone (FMK) that preferentially binds covalently to the active caspase 1 and is visualized by fluorometry, fluorescence microscopy, or flow cytometry.
FLICA Caspase Assay detects active caspases inside the cell using novel Fluorochrome Inhibitor of Caspases (FLICA)-cell permeable and non-cytotoxic caspase inhibitors. Once inside the cell, the FLICA probe covalently binds to a reactive cysteine residue on the large subunit of the active caspase heterodimer, thereby inhibiting further enzymatic activity. Bound FLICA is retained within the cell, while any unbound reagent is washed away. The bound FLICA emits a green fluorescent signal, which is a direct measurement of the number of active caspase molecules that are present in the cell at the time the reagent was added.