Human caspase 3 (CASP3), also known as CPP32 and apopain, a.a. 1 - 277 (end) (GenBank Accession No. NM_004346, var alpha) with C-terminal His-tag, expressed in an E. coli expression system. Procaspase-3 is self-cleaved into two subunits, MW = 17 kDa and 13 kDa, to form the active heterotetrameric complex.