4-Nitrophenyl phosphate (pNPP) is a chromogenic substrate for alkaline phosphatase.1 Upon hydrolysis by alkaline phosphatase, 4-nitrophenol is released, which can be quantified by colorimetric detection at 405 nm as a measure of alkaline phosphatase activity. It has been commonly used in ELISAs.
1.Lorenz, U.Protein tyrosine phosphatase assaysCurr. Protoc. Immunol.9311.17.11-11.17.12(2011)
















