Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fru
ID: 100555 • Letter: P
Question
Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group during glycolysis. Adenosine monophosphate (AMP) binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate. ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate.
a. What is the role of AMP in this example? Explain
b. What is the role of ATP in this example? Explain
Explanation / Answer
Answer:
Metabolic pathway is often controlled by enzymatic reaction. ATP is generated due to fegradation of glucose. Here in glycolysis the reactions is catalyzed by hexokinase, phosphofructokinase (PFK) etc. so It has the catalytic role and as well as regulation type of role so that it can inhibit the reaction for proper control.
a) here AMP generally reverse the inhibitory action of ATP and this reverse process is increased when the ATP/AMP ratio is lowered. We can also say it will increase the rate of glycolysis. if AMP is high then the energy charge falls. So fructose 1,6-bisphosphate will form.
b) high levels of ATP generally allosterically inhibit the activity of PFK enzyme. So therefore the affinity towards fructose 6-phosphate is going to be low in this case. So fructose 1,6-bisphosphate will not form.
We can also see the graph for comparision, so if the concentration of ATP is high then ATP converts the hyperbola binding curve of fructose 6-phosphate into a sigmoidal type of graph. Citrate enzyme generally helps for this conversion. Here ATP binds to the specific regulatory site which is distinct from catalytic site of enzyme and inhibits the activity of PFK.