Caspase-9 is a member of the interleukin-1beta converting enzyme (ICE) family of cysteine proteases. Similar to other caspases, caspase-9 also exists in cells as an inactive proenzyme. During the initiation of apoptosis the proenzyme is processed at aspartate residues to form active caspase-9. As one of the initiator caspases, active caspase-9 functions to trigger the activation of downstream effector caspases and further lead to disassembly of cell structures.

The partially purified active recombinant human caspase-9 with full-length HIS-6 tag was expressed in E. coli. The expressed caspase-9 spontaneously undergoes autoprocessing to yield the subunits characteristic of the native enzyme. In combination with caspase-9 activity assays, the active recombinant caspase-9 is useful in biological screening of caspase inhibitors. The recombinant enzyme can also be used as a positive control in caspase-9 assays. Caspase 9 is known to have strong reactivity with other sequence peptides, especially DEVD-pNA.

Product Source: Human

Enzyme is prepared as an activity standard only, any other application not tested. Caspase-9 is subject to auto-activation thus active caspase subunits and partially active intermediates will be seen. Bands of approximately 45kDa (pro), 35kDa (partially active) and 18kDa + 12kDa (large and small subunits) may be seen by western blot depending upon the antibody used. The small subunit is extremely difficult to detect in most westerns.

Activation: incubate 1-5 μL of stock in PBS pH 7.5 (100mM HEPES can be used as well) plus 10mM ATP and 5mM DTT (added just before use) for 30 minutes at 37°C.

Lyophilized. Reconstitute with 25 μl of PBS + 15% glycerol.

Maintain at -70°C in undiluted aliquots for 3-6 months from date of receipt. Avoid repeated freeze/thaw cycles.

Also contains E. coli proteins.Approximately, 0.8-2 μg total protein / unit of activity.

Specific Activity: One unit of the recombinant caspase-9 is the enzyme activity that cleaves 1 nmol of the caspase substrate LEHD-pNA (pNA: pnitroanaline) per hour at 37°C at saturated substrate concentrations.

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