Figure 3: Dephosphorylation of a phosphopeptide substrate pp10 by hCaMKP-N(WT) and hCaMKP-N(1–559). The indicated concentrations of pp10 were dephosphorylated by hCaMKP-N(WT) (open circles) and by hCaMKP-N(1–559) (closed circles) at 30˚C as described in Section 2. The amount of inorganic phosphate released in the reaction mixture during the reaction was determined as described. The indicated curves were obtained by direct fits of the data to Michaelis-Menten equation. The data shown are those in a representative experiment of at least three independent determinations with similar results.