Caspase-3 is an active cell-death protease involved in the execution phase of apoptosis, during which cells undergo morphological changes such as DNA fragmentation, chromatin condensation, and apoptotic body formation ^{(1, 2)}. Caspase-3 DEVD-R110 Fluorometric and Colorimetric Assay Kit provides a simple assay system for fast and highly sensitive detection of caspase-3 activity either by fluorescence or absorbance in mammalian cells. The fluorogenic and chromogenic substrate (Ac-DEVD)2-R110 contains two DEVD tetrapeptides and is completely hydrolyzed by the enzyme in two successive steps ^{(3, 4)}. Cleavage of the first DEVD peptide results in the monopeptide Ac-DEVD-R110 intermediate, which has absorption and emission wavelengths similar to those of R110 (l_ex\l_em= 496/520 nm) but has only about 10% of the fluorescence of the latter. Hydrolysis of the second DEVD peptide releases the dye R110, leading to a substantial fluorescence increase

Although fluorometric detection of the end products is preferred because of the superior sensitivity, detection by absorbance is also possible. In fact, the extinction coefficient of R110 is 10 times higher than that of p-nitroaniline (pNA), a dye commonly used in chromogenic substrates, making R110- based substrates significantly more sensitive than pNA-based substrates, even by colorimetric detection.

The assay kit includes Ac-DEVD-CHO, which is a caspase-3 inhibitor and can be used as a negative control. Also, R110 is provided in the kit for generating a standard curve, which can be used for quantifying caspase-3 activity.