What is the Difference Between PFK-1 and PFK-2?

The main difference between phosphofructokinase-1 (PFK-1) and phosphofructokinase-2 (PFK-2) lies in their catalytic functions and regulation:

1. Catalytic Functions:

• PFK-1 catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, which is the rate-limiting step of glycolysis.
• PFK-2 catalyzes the conversion of fructose-6-phosphate to fructose-2,6-bisphosphate.

1. Regulation:

• PFK-1 activity is affected by ATP concentration, while PFK-2 activity is not.
• PFK-2 has both kinase and phosphatase activity, making it a bi-functional enzyme.
• Fructose 2,6-bisphosphate, a product of PFK-2, is a powerful allosteric activator of PFK-1.

In summary, PFK-1 and PFK-2 are both involved in the regulation of glycolysis, but they catalyze different reactions and are regulated differently. PFK-1 is responsible for the rate-limiting step of glycolysis, while PFK-2 plays a role in activating PFK-1 through the production of fructose 2,6-bisphosphate.

Comparative Table: PFK-1 vs PFK-2

The key difference between PFK-1 and PFK-2 lies in their specific roles in the glycolysis pathway and their regulation:

Both PFK-1 and PFK-2 use the same substrate, fructose 6-phosphate, and add an extra phosphate to the substrate during phosphorylation. However, the products of their reactions and their roles in glycolysis are different.