Used in enzymatic assays to detect protease activity, particularly for serine proteases such as trypsin and thrombin. The compound acts as a chromogenic substrate—when cleaved by the target enzyme, it releases p-nitroaniline (pNA), a yellow-colored product that can be measured spectrophotometrically at 405 nm. This allows for real-time monitoring of enzyme kinetics and inhibition studies. Commonly employed in high-throughput screening, drug development, and biochemical research to assess enzyme function and specificity. The p-tosyl group enhances substrate selectivity for certain proteases, making it a valuable tool in diagnostic and analytical applications.