Which Regulatory Enzyme Shows Greater Activity at Low Energy Charge

Question

Which regulatory enzyme shows greater activity at low energy charge in an energy-producing pathway?
A)hemoglobin
B)phospholipase C
C)PKA
D)PFK-1

Accepted Answer

PFK-1 (phosphofructokinase-1) is a key regulatory enzyme in the glycolysis pathway that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. PFK-1 is allosterically activated by AMP and inhibited by ATP, making it responsive to changes in cellular energy charge. At low energy charge, there is a relatively high concentration of AMP, which allosterically activates PFK-1, thereby enhancing the rate of glycolysis to generate more ATP. Hence, choice D is the correct answer. Hemoglobin is a protein involved in oxygen transport and has no role in energy-producing pathways. Phospholipase C is involved in signal transduction pathways, and PKA (protein kinase A) is an enzyme that phosphorylates target proteins in response to intracellular cAMP levels. Although they are involved in cellular signaling, they do not play a direct role in energy-producing pathways.