6. Enzymes and Enzyme Kinetics

An enzyme-catalyzed reaction was carried out with a [substrate] initially 1000 times greater than the Km for that enzyme. After 9 minutes, 1% of the total substrate was converted into 12 μmoles of product. 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 of product (12 μmoles) to be formed?

A) Suppose the [S] = 10 K_m. Use the Michaelis-Menten equation to determine what percentage of the V_max will be equal to the value of V ₀.

B) Now suppose the [S] = 20 K_m. Use the Michaelis-Menten equation to determine what percentage of the V_max will be equal to the value of V ₀. What conclusion can be made from these calculations?

An enzyme catalyzes a reaction at a velocity of 10 μmol/min when all enzyme active sites are occupied with substrate. The K_m for this substrate is 1 x 10^-5 M. Assume that Michaelis-Menten kinetics are followed, calculate the initial reaction velocity (V₀) when:

A) [S] = 1 x 10^-5 M. V₀ = ___________ 

B) [S] = 1 x 10^-2 M. V₀ = ___________

What is the ratio of [S] to K_m ( [S] / K_m ) when the V₀ of an enzyme-catalyzed reaction is 80% of the V_max?

Which of the following statements about a V₀ vs. [S] plot for a Michaelis-Menten enzyme is false?