Protein phosphatase 1 (PP1) catalyzes a reaction which yields products that regulate cell division; consequently, PP1 is a possible drug target to treat certain types of cancers. The PP1 enzyme cata- lyzes the hydrolysis of a phosphate group from myelin basic protein (MBP). The reaction is shown below: PP1 MBP-phosphate-→ MBP+P,
The activity of PP1 was measured in the presence and absence of the inhibitor phosphatidic acid (PA). The concentration of PA was 300 nM. vo without PA vo with PA released . (mg/mL) mL"1 . min1) mL-1 . min-1) 0.00381 0.00620 0.00931 0.0140 0.010 0.0209 0.0335 0.0419 0.0838 0.015 0.025 0.050
(a) Use the data provided to construct a Lineweaver-Burk plot for the PP1 enzyme in the presence and absence of PA. What kind of inhibitor is PA?
(b) Report the KM and Vmax values for PP1 in the presence and absence of the inhibitor.