Enzyme Kinetics Problems
For each Problem Make 2 Graphs:
A. PLOT Vo versus [S] to show that the enzyme obeys Michaelis-Menten Equation.
B. PLOT 1/Vo versus 1/[S] to determine Km and Vmax.
1. The following kinetic data were collected:
2. The kinetics of an enzyme were analyzed in the absence and presence of inhibitors A and B.
A. What type of inhibitors are A and B: Competitive or Non-Competitive?
(Use your graphs to answer this question)
B. In addition to calculating Km and Vmax in the absense of inhibitors, calculate the Ki constants for the inhibitors A and B.
Equations for calculating inhibition constants (ie Ki values).
Competitive Inhibition: Km' = Km (1 + [I]/Ki)
Non-Competitive Inhibition: Vmax' = Vmax/(1 + [I]/Ki)
To calculate the Ki for inhibitors A and B, use one of these 2 equations and the kinetic constants for the uninhibited reaction (ie Km and Vmax), along the Km' and Vmax' obtained in the presence of each inhibitor. For the inhibitors, use the concentration of inhibitor s in the calculation of Ki; for inhibitor A, [I] = 5 mM; for inhibitor B, [I] = 0.1 mM.
3. For more pratice, do problem 4(a), shown below.
Problem 4(a) is taken from Voet & Voet, last year's textbook.
More practice problems will be given in the form of problems from previous exams.
©Wilbur H. Campbell, 1995; wcampbel@mtu.edu