Answer to Question #83754 in Biochemistry for Effah George

Question

If you were studying an enzyme that catalyzed the reaction of ATP and fructose 1-
phosphate to form fructose 1,6-bisphosphate and ADP and discovered that a plot of the
initial velocity of formation of fructose 1,6-bisphosphate versus ATP concentration was
not hyperbolic, but rather sigmoid, what would you suspect?

Answer 1

Sigmoidal velocity of formation of the end product can be explained by high concentration of ATP.

ATP causes this effect by binding to a specific regulatory site of enzyme, which is distinct from the regulatory site. Hence the high concentration of ATP has an inhibitory effect on velocity of reaction.