PCAT Biological Processes – DFP
- Dec 18, 2017
- PCAT Question of the Day
Diisopropylfluorophosphate (DFP) binds to the active site of acetylcholinesterase (ACE) in the synapses of neurons. When DFP binds to ACE, the ACE enzyme is rendered permanently inactive. This makes DFP a potent toxin, with lethal amounts at less than 100 mg. The interaction between DFP and ACE can best be characterized as:
A) Competitive inhibition
B) Noncompetitive inhibition
C) Irreversible inhibition
D) Partially competitive inhibition
Click for Explanation
The binding described involves the inhibitor binding to the enzyme and rendering the enzyme permanently inactive. That’s the definition of irreversible inhibition, making C the correct answer.
A: Competitive inhibitors bind to the active site but bind reversibly: they do not permanently disable the enzyme. By adding very high levels of the normal substrate, the effects of competitive inhibitors can be overcome.
B: Noncompetitive inhibitors bind to a site other than the active site.
D: Partially competitive inhibitors bind to a site other than the active site and allow the enzyme to still have some catalytic activity (typically reduced, but possible to be higher).
Search the Blog
Free ConsultationSchedule Now
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More