pNPA

pNPA, or para-nitrophenyl acetate, is a synthetic organic compound. It is an ester derived from para-nitrophenol and acetic acid. pNPA is a colorless solid at room temperature and is soluble in many organic solvents. Its primary use is as a substrate in enzymatic assays, particularly for the detection and quantification of esterase activity. When an esterase enzyme cleaves the ester bond in pNPA, it releases para-nitrophenol, which is a yellow-colored compound. The intensity of the yellow color, measured spectrophotometrically at a specific wavelength (typically around 400-410 nm), is directly proportional to the amount of enzyme activity present. This chromogenic property makes pNPA a convenient and widely used tool in biochemistry and molecular biology research. It is also employed in some industrial quality control processes where esterase activity needs to be monitored. The rate of pNPA hydrolysis can be used to determine enzyme kinetics, such as Vmax and Km values.