Question

Phosphofructokinase catalyzes the phosphorylation of fructose 6‑phosphate to fructose 1,6‑bisphosphate in glycolysis. Fructose 1,6‑bisphosphatase catalyzes the hydrolysis of fructose 1,6‑bisphosphate to fructose 6‑phosphate in gluconeogenesis.

fructose 6- phosphate
phosphofructokinase fructose 1 ,6-bisphosphatase
fructose 1,6 - bisphosphate
How does fructose-2,6-bisphosphate (F26BP) affect the activity of the enzymes phosphofructokinase-1 (PFK) and fructose I ,6-bisphosphatase (FBPase)?
a. increases PFK activity, increases FBPase activity
b. decreases PFK activity, increases FBPase activity
c. decreases PFK activity, decreases FBPase activity
d. increases PFK activity, decreases FBPase activity

Answer 1

d. increases PFK activity, decreases FBPase activity

Step-by-step explanation:

Fructose-2,6-bisphophate is formed by the phosphorylation of fructose-6-phosphate catalyzed by phosphofructokinase-2, PFK-2.

Fructose-2,6-bisphophate functions as an allosteric effector of the enzymes phosphofructokinase-1, PFK-1 and fructose-1,6-bisphosphatase, FBPase.

Fructose-2,6-bisphophate has opposite effects on the enzymes, PFK-1 and FBPase. When it binds to the allosteric site of the enzyme, PFK-1, it increases the enzymes's activity by increasing its affinity for its substrate fructose-6-phosphate and reduces its affinity for its allosteric inhibitors ATP and citrate. However, when it binds to FBPase, it reduces its activity by reducing its affinity for glucose, its substrate