An enzyme-catalyzed reaction was carried out with the substrate concentration in
ID: 598184 • Letter: A
Question
An enzyme-catalyzed reaction was carried out with the substrate concentration initially 1,000 times greater than the Km for that substrate. After 9 minutes, 1% of the substrate had been converted to product, and the amount of product formed in the reaction mixture was 12 micro-moles. If, in a separate experiment, one-third as much enzyme and twice as much substrate had been combined, how long would it take for the same amount (12 micro-moles) of product to be formed?the answer is 27 minutes, how do I solve this?
Explanation / Answer
Since the concentration of the substrate in the initial experiment was 1000 time greater than the Km, we had it set up so that the rate of the reaction basically depended entirely on the concentration of the substrate and not on the concentration of the enzyme. In the second experiment, we decrease the concentration of the enzyme, but increase the substrate concentration. Since we had saturated the enzyme in the first experiment, it will definitely be saturated this time as well. That means that we can expect the rate of the second reaction to be linearly related to the rate of the first. So if the concentration was C in the first reaction and it took 9 mins, and we know that the concentration in the second reaction is C/3. Since we have divided the concentration by 3, we expect the time required to increase by the same factor. 9*3 = 27 min