4-Nitrophenyl acetate

4-Nitrophenyl acetate is a chromogenic substrate widely used in enzymology, analytical chemistry and biochemical research. Upon hydrolysis by esterases, lipases and other hydrolase enzymes, it releases the chromophore 4-nitrophenol, which can be readily monitored spectrophotometrically at 405 nm due to its strong absorbance in alkaline solution. The enzymes initially release 4-nitrophenol. The assay is then performed or stopped under alkaline conditions, converting it to the p-nitrophenoxide ion, which has a strong absorbance at 405 nm. This is why enzyme activity is almost always monitored at 405 nm. This property makes 4-nitrophenyl acetate an ideal substrate for enzyme activity assays, kinetic studies, inhibitor screening and method development. It is also used as an intermediate in organic synthesis and chemical research.