Z-IETD-pNA is primarily used as a substrate in biochemical assays to measure the activity of granzyme B, a serine protease involved in immune responses. It is commonly employed in research to study apoptosis, particularly in the context of cytotoxic T-cell and natural killer cell-mediated cell death. The substrate’s cleavage by granzyme B produces a detectable colorimetric signal, making it valuable for high-throughput screening and kinetic studies. It is also utilized in drug discovery to evaluate inhibitors of granzyme B, which may have therapeutic potential in autoimmune diseases and cancer. Additionally, it aids in understanding the role of granzyme B in various pathological conditions, including inflammation and tissue damage.