Protein Phosphatase, Mg2+/Mn2+ Dependent 1H (PPM1H)

PPM1H possesses the potential to dephosphorylate p-nitrophenyl phosphate, casein and phosphopeptides. PPM1H shows the metal preference that is varied depending on the substrate; PPM1H prefers Mn(2+) when pNPP or phosphopeptides is used as a substrate. Meanwhile, a preference for Mg(2+) is displayed by PPM1H with casein as a substrate. When both cations are added to the reaction, the degree of the effect is always closer to that with Mn(2+) alone, irrespective of the substrate. This preponderance of Mn(2+) is explained by its greater affinity for PPM1H than Mg(2+). From the literature the substrate-dependent metal preference appears to be shared by other PP2Cs. According to the crystal structure, a binuclear metal center of PP2C plays an important role for coordinating the substrate and nucleophilic waters in the active site.