For her undergraduate project, Jessica studied an enzyme that catalyzes the reaction AE B For substrate A, she determined that Km 3.0 M and koat30 min. Jessica graduated and her project has been passed on to you. Unfortunately, Jessica was so busy that she sometimes forgot to record all of the details of an assay in her lab notebook. Your mentor suggests that you try to back calculate some of the missing concentration values. Assume that the enzyme follows Michaelis-Menten kinetics In one experiment where [A] = 4 mM, she found that the initial velocity, Vo was 324 nM min What was the [Et] she used in this experiment? In another experiment with [E] = 0.3 uM, she found that Vo = 4 μM min-1 What was the [A] she used in this experiment? Number Number The compound Z was found to be a very strong competitive inhibitor of the enzyme, with an α of 10 In an experiment with the same [Eas in part (a,bMenten curve at low [Sj, the second order rate a different [A], an amount of Z is added that reduces the rate Vo to 162 nM min What was the [A] in this experiment? A measure of the catalytic efficiency of an enzyme is the initial slope of the Michaelis- constant kcat/Km- A "perfect" enzyme, limited only by diffusion, would have a value of 10s or 109 M's-1. Calculate kcat/Km for this enzyme Number Number M-s-1
