An enzyme-catalyzed reaction was carried out with the substrate concentration initially a thousand times greater than the K_m 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 $\mu$mol. 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$\mu$mol) of product to be formed? A) 1.5 min B) 13.5 min C) 27 min D) 3 min E) 6 min

Question

Quizplus · Accepted Answer

The initial substrate concentration was a thousand times greater than the K_m, which means the enzyme was saturated with substrate. Therefore, the reaction rate was at its maximum and the substrate concentration was not a limiting factor. After 9 minutes, 1% of the substrate had been converted to product. This means that 99% of the substrate is still available for reaction. The amount of product formed in the reaction mixture was 12 F1F1F1S1F1F1F10mol. This means that the total amount of product that can be formed from the initial substrate concentration is 1200 F1F1F1S1F1F1F10mol (since only 1% of the substrate has been converted to product). In the second experiment, the enzyme concentration is one-third of the original concentration and the substrate concentration is twice the original concentration. This means that the enzyme concentration is limiting and the substrate concentration is not. Since the same amount of product (12 F1F1F1S1F1F1F10mol) is formed in both experiments, the rate of product formation must be the same in both experiments. In the second experiment, the enzyme concentration is one-third of the original concentration, so the rate of product formation will be three times slower than in the first experiment. Therefore, it will take three times longer to form the same amount of product, which is 27 minutes. Therefore, the answer is (C) 27 min.

An Enzyme-Catalyzed Reaction Was Carried Out with the Substrate Concentration μ\muμ

An Enzyme-Catalyzed Reaction Was Carried Out with the Substrate Concentration $\mu$