Protein phosphatases regulate fundamental biological processes such as cell proliferation and differentiation in cooperation with protein kinases. Protein phosphatases consist of three general families with different substrate specificities towards phospho-seryl/threonyl, -tyrosyl residues, or both.

This kit provides a simple means to measure phosphatase activity by using pNPP as a general substrate of phosphatases.

In a first step, the enzyme dephosphorylates its substrate pNPP. In a second step, the phenolic OH-group is deprotonated under alkaline conditions resulting in p-nitrophenolate with a strong absorption at 405 nm (yellow) (see figure on the right).

Diagram on the left: Phosphatase SHP-1 (100 ng) was assayed with 10 mM pNPP in JBS Phosphatase Assay. This type of assay is called “end-point” assay since the activity of the enzyme is evaluated after a given time of reaction (here: 5, 10, 30 and 60 min).

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