Question

Acetylcholinesterase is an enzyme that catalyzes the breakdown of the neurotransmitter acetylcholine. Which of the following explains why acetylcholinesterase cannot be used to catalyze the breakdown of other neurotransmitters, like norepinephrine?

It would require a level of activation energy too high for acetylcholinesterase to react with other neurotransmitters.
      Binding with an alternate neurotransmitter would inhibit the reaction of the enzyme with acetylcholine.
      Reacting with another neurotransmitter would halt the production of the enzyme and raise the overall activation energy.
      Its shape determines the neurotransmitters that can reach its active center where activation energy is lowered.

I think it might be the last one

Answer 1

Its shape determines the neurotransmitters that can reach its active center where activation energy is lowered.

Answer 2

"Its shape determines the neurotransmitters that can reach its active center where activation energy is lowered" definitely best explains why acetylcholinesterase cannot be used to catalyze the breakdown of other neurotransmitters, like norepinephrine. You were right. Good job. :)