Question

A plot of enzyme velocity against temperature for an enzyme indicates little activity at 0 degrees Celsius and 40 degrees Celsius, with peak activity at 35 degrees Celsius. The most reasonable explanation for the low velocity at 0 degrees Celsius is that __________.

a. both the frequency and energy of enzyme-substrate collisions are low
b. substrate binding at the active site is thermodynamically unfavorable at low temperature
c. the hydrogen bonds that define the enzyme's active site are broken as temperature increases
d. the enzyme was denatured at this temperature

Answer 1

The most reasonable explanation for the low enzyme velocity at 0 degrees Celsius is that both the frequency and energy of enzyme-substrate collisions are low, inhibiting the formation of enzyme-substrate complexes necessary for the reaction to proceed efficiently.

Step-by-step explanation:

The low enzyme velocity at 0 degrees Celsius can be explained by the fact that at low temperatures, both the frequency and energy of enzyme-substrate collisions are low, which means fewer enzyme-substrate complexes are formed and those that are formed have insufficient kinetic energy to overcome the activation energy of the reaction.

At very low temperatures, like 0 degrees Celsius, the molecular motion is significantly reduced, limiting these productive collisions. In contrast, at high temperatures, enzymes may become denatured, leading to a loss in their specific three-dimensional structure that is necessary for the catalytic activity, but this denaturation is not the reason for low activity at 0 degrees Celsius.