Metabolism & Bioenergetics MCAT Practice Question
A biochemistry student measures enzyme activity for phosphofructokinase-1 (PFK-1), a key regulatory enzyme in glycolysis, under varying concentrations of ATP and AMP. The student observes that PFK-1 activity increases dramatically when AMP concentrations rise relative to ATP. This represents allosteric regulation reflecting the cell's energy status. Which of the following best describes the mechanistic basis for this allosteric activation?
Answer choices
- AAMP competes with substrate fructose-1,6-bisphosphate for the active site
- BAMP decreases the Km of PFK-1 while increasing Vmax proportionally
- CATP phosphorylates PFK-1, reducing its catalytic efficiency irreversibly
- DAMP binding to an allosteric site causes conformational change that increases substrate affinityCorrect answer
- EAMP acts as a competitive inhibitor by binding near the active site
- FAMP directly reduces ATP's inhibitory effect by forming a complex that sequesters ATP away from PFK-1
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