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Unformatted text preview: Problem Set 3 1) You are studying an enzyme, Glucose Isomerase, which converts glucose to fructose. To study the kinetics of the enzyme, you mix a small amount of enzyme with various concentrations of glucose and measure the reaction rate. You obtain the following results. [S] = [glucose, v=velocity. a. Estimate Vmax and Km for the data by plotting v as a function of [S] Eyeballing, can guess curve flattens out at about Vmax = 150 M/min, in which case Km is about 25 M. b. A Lineweaver-Burke plot [S] M v M-min-1 5 22 10 39 20 65 50 102 100 120 200 135 Page 1 of 6 Problem Set 6 3/4/2010 http://www.michaelpready.com/mready/ProblemSet3Spring09Key.htm Vmax = 1/0.0061 = 164; Km/Vmax = 0.1961, so Km = 164*.1961 = 32 By the way, there is also another plot called an Eadie-Hofstee plot, which I blew off for time constraints, which is commonly used and plots v vs. v/[S]. The y-intercept is Vmax and the slope is Km. Km is about 30, Vmax is about 158 2) In your experiment, the total concentration of Glucose Isomerase is 1 nM. a. How many reactions can an enzyme catalyze in 1 minute? (i.e. what is k cat ) If we average the results from b and c above, we get Vmax = 161 M/min and Km = 31...
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