The enzyme phosphoserine phosphatase catalyses the reaction: phosphoserine+ H2O serine + Pi Kineties measurements were performed using a range of Mg" concentrations andin the presence of different fixed concentrations of

Ca". The enzyme requiresMg" for activity. The following data were recorded: What type of inhibitor is Ca?+ and what is its Kj? Suggest what role Mg performs in the catalytic mechanism of phosphoserinephosphatase. Suggest how Ca inhibits the reaction.