pNPP

pNPP (para-Nitrophenyl Phosphate) is a chromogenic substrate used in spectrophotometric assays to measure the activity of phosphatases, particularly alkaline phosphatases (AP) and protein tyrosine phosphatases (PTP). When hydrolyzed by a phosphatase, pNPP yields a yellow, water-soluble product, para-nitrophenol, which can be quantified by measuring absorbance at 405 nm. This assay is widely used in ELISA and other immunoassays, allowing for the detection of phosphatase activity in various applications, such as protein detection and enzyme activity profiling