Activation of caspase-9 (CASP9) through apoptotic stimuli initiates the caspase cascade. Caspases have been implicated in many disorders including cancer, inflammatory disease, neurodegenerative diseases, stroke and myocardial infarction.

When cells receive apoptotic stimuli, such as activation of the TNFα/Fas cell surface receptor, caspase 8 activation, Bid processing and its translocation to the mitochondria ensue. As a result mitochondria release cytochrome c which then binds to Apaf-1, the mammalian Ced-4 homologue, together with dATP. The resultant complex recruits caspase 9 leading to its activation. It then cleaves downstream caspases such as caspase 3, 6, and 7, initiating the caspase cascade. Caspase 9 exhibits basal activity. It can be further activated via interaction of its N-terminal prodomain with the activator protein Apaf-1 in the presence of cytochrome c and dATP. Caspases have been implicated in many disorders including cancer, inflammatory disease, neurodegenerative diseases, stroke and myocardial infarction.

Solution in 10% sucrose containing 50 mM HEPES, pH 7.5, 5 mM DTT, 0.1% CHAPS, 1 mM EDTA, 50 mM NaCl.

One unit will cleave 1.0 nmol of Ac-Leu-Glu-His-Asp-AFC per hr at 25 °C at pH 6.5.