Properties of the caspases.

Caspases comprise a structurally related group of cysteine proteases that share a dominant primary specificity for cleaving peptide bonds following Asp residues. Present in the cytosol of all animals, the caspases participate in proteolytic pathways required for executing programmed cell death, or apoptosis. In mammals the caspases have also evolved a function in activating proinflammatory cytokines. We review the current knowledge of the substrate specificity, structure, and activation mechanisms of human caspases and relate these findings to their fundamental biologic role.