Question

An extremely efficient enzyme called "efficase" catalyzes the conversion of "A" to"B." A researcher decides to mutate the enzyme in order to try to improve itperformance. Following active site mutations, a significant reduction in the value ofKm and Vmax was observed. Which of the following may have occurred?Select one:a. The affinity of the enzyme for the substrate was increased to a point whichdid not favor propagation (continuation) of the reaction.b. The decrease in Vmax was not related to the decrease in Km.c. If the reaction was first­order, the change in Km cannot have affected Vmax.d. The stability of E+S (E + A as written above) was increased, therebyincreasing the Km.e. The reverse reaction (breakdown of E+A) was favored, slowing the Vmax.

Answer 1

Answer:

The answer to this question on the effects of mutation of the enzyme on the reduction of the Km and Vmax is that the affinity of the enzyme for the substrate was increased to a point which did not favor the propagation of the reaction: A

Explanation:

The Km is the concentration of the substrate needed by an enzyme to reach half of its maximum velocity (Vmax) when this parameter (Km) is high; it means that the enzyme needs more of the substrate to reach a reasonable rate of its action, either catabolic or anabolic effect. Hence, the enzyme has a low affinity to the substrate. The mutation of the genetic codes responsible for the translation of the enzyme in this experiment that leads to the reduction of the Km, therefore, had resulted in the increase in the affinity of the enzyme to the substrate. Therefore tiny molecules of the substrate will be needed by the enzyme to reach half of its maximum rate. This increased affinity, however, is too high such that the production of E + P is delayed due to the inability to release the enzyme. Therefore, the effect is not favorable for the continuation of the reaction.