Used in biochemical assays to study the activity of cathepsin D and E proteolytic enzymes. This substrate contains a fluorescence resonance energy transfer (FRET) pair, enabling real-time monitoring of enzyme activity by detecting the increase in fluorescence upon peptide cleavage. Commonly applied in drug discovery and development to screen inhibitors of cathepsin D and E, which are implicated in diseases such as cancer, autoimmune disorders, and neurodegenerative conditions like Alzheimer's disease. Also utilized in cellular and tissue studies to assess lysosomal protease function and pathway regulation.