Caspases contain which of the following amino acids in their active site?

A feature of apoptosis is the activation of several members of a family of cysteine proteases named caspases. The term caspase is based on two propeies of this family of enzymes: the "c" refers to a cysteine protease (i.e., an enzyme with cysteine in its active site), and "aspase" refers to the unique ability of these enzymes to cleave after aspaic acid residues. The presence of cleaved, active caspases is a marker for cells undergoing apoptosis. Ref: Robbins 8th edition, Chapter 1.