MathBench > Cellular Processes

Enzyme Kinetics

Part IV: Virtual Experiment, Real Enzymes

The last 18 or so pages were just the groundwork for the interesting part: using the values of Vmax and Km to infer interesting information about an enzyme - substrate system.

I promised we would consider a real enzyme, so here it is: o-diphenol oxidase, the enzyme responsible for shoving oxygen molecules onto phenol rings, thereby coincidentally turning them brown. The brown part is not terribly important to the apple, but to the scientist, it offers a convenient way to measure the amount of product present, and hence the rate of the reaction. (After all, counting phenol rings would be rather tedious, even if they were big enough to see in a microscope).

First experiment: o-diphenol oxidase on apples

Your mission: choose 4 concentrations of substrate. For each concentration, press "go" to simulate the reaction and find out what the spec readings were. Calculate the rate of reaction. Use the Lineweaver-Burke plot to determine Km and Vmax for the reaction.

The Original Data
trial 1 2 3 4 5
[S] 10 20 30 40 50
V 21 30 41 45 49
The Transformed Data
trial 1 2 3 4 5
1/[S]
1/V

Vmax:   Km:  

The Plots