L-Proline p-nitroanilide trifluoroacetate salt is primarily used in biochemical research as a substrate for studying enzyme activity, particularly for proteases and peptidases. It serves as a chromogenic substrate, enabling the detection and quantification of enzymatic reactions through colorimetric assays. When the enzyme cleaves the compound, it releases p-nitroaniline, which can be measured spectrophotometrically due to its distinct absorbance in the visible range. This makes it a valuable tool in enzyme kinetics studies, inhibitor screening, and characterizing the specificity of proteolytic enzymes. Its application is critical in understanding enzyme mechanisms and developing therapeutic agents targeting enzyme-related diseases.