Cathepsin D, derived from bovine spleen, is widely utilized in biochemical research for its proteolytic activity. It plays a crucial role in studying protein degradation pathways, particularly in understanding lysosomal function and intracellular protein turnover. This enzyme is also employed in the investigation of apoptosis, as it is involved in the cleavage of specific substrates during programmed cell death. Additionally, Cathepsin D is used in the development of assays to measure its activity, which can be indicative of certain disease states, such as cancer and neurodegenerative disorders. Its application extends to the food industry, where it aids in the tenderization of meat by breaking down muscle proteins. Furthermore, it serves as a model enzyme in the study of protease inhibitors, contributing to the design of therapeutic agents targeting proteolytic enzymes.