Return to Blog Homepage

MCAT Biology Question — DFP

  • by John
  • Oct 17, 2014
  • MCAT 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

 

Explanation

The binding described involves the inhibitor binding to the enzyme and rendering the enzyme permanently inactive. That’s the definition of irreversible inhibition.

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).

Want more MCAT practice?

We’ve got options for every schedule and learning style!

From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!

Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.

Submit a Comment