~10,000 units/mg. One unit cleaves 1nmole of the caspase substrate VDVAD-pNA per hour at 37°C in a reaction solution containing 50mM HEPES, pH 7.2, 50mM NaCl, 0.1% CHAPS, 10mM EDTA, 5% glycerol and 10mM DTT.
Caspase-2 (also known as Ich-1, Nedd-2) is a member of the interleukin-1 converting enzyme (ICE) family of cysteine proteases. Similar as other caspases, caspase-2 also exists in cells as an inactive proenzyme. During apoptosis, procaspase-2 is processed at aspartate residues by self-proteolysis and/or cleavage by upstream caspases. The processed form of caspase-2 consists of large (19 kDa) and small (12 kDa) subunits, which associate to form the active enzyme. The active recombinant human caspase-2 was expressed in E. coli. The expressed caspase-2 spontaneously undergoes auto-processing to yield the subunits characteristic of the native enzyme.