Caspases are cysteine-dependent aspartate-directed proteases responsible for the proteolysis of a plethora of substrates during programmed cell death. These include structural proteins of the cytoplasm and nucleus, components of the DNA repair machinery, protein kinases, signalling proteins and regulatory proteins. Caspases are synthesised as relatively inactive zymogens, that become activated by scaffold-mediated transactivation or via cleavage by upstream proteases in an intracellular cascade. The resulting heterotetrameric enzymes possess a unique absolute requirement for aspartate at the substrate cleavage site, and recognise a tetrameric sequence within the substrate. In order to assess the role of caspases in apoptotic execution, I set out to evaluate the synthesis of novel caspase inhibitors, which would enable the detection of active caspases from apoptotic whole cell extracts. First a 2,4-dinitrophenyl probe was designed for the affinity tagging of caspases in two-dimensional gel electrophoresis. Second, biotinylated peptidylaldehydes were prepared which will enable the affinity purification of caspases from apoptotic cytosolic extracts under non-denaturing conditions. To enable biochemical studies of caspases, I developed a method, which permits the affinity purification of caspases. Apoptotic chicken hepatoma cell-line extracts were purified over an avidin column using a biotinylated probe. Finally, to permit the appraisal of the caspase proteomic variability between different cell types, and methods of apoptotic induction, and the identification of post-translational modifications of caspases, I developed a reproducible system for the identification of caspases by two-dimensional gel electrophoresis.