Which enzyme serves as the catalyst in the first committed step of glycolysis?

The first committed step of glycolysis is catalyzed by phosphofructokinase-1 (PFK-1), which is a key regulatory enzyme in the pathway. This step involves the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate, using ATP as a phosphate donor. This reaction is critical because it effectively commits the substrate to the glycolytic pathway, as once fructose-1,6-bisphosphate is formed, it cannot easily revert to glucose-based intermediates.

Phosphofructokinase-1 operates as a crucial control point in glycolysis, responding to cellular energy levels. It is activated by molecules such as AMP and fructose-2,6-bisphosphate when the cell needs to increase glycolytic flux for energy production. Conversely, it is inhibited by ATP and citrate, indicating sufficient or excess energy levels in the cell. This regulatory role positions PFK-1 as the "bottleneck" in the glycolytic pathway, ensuring that the metabolic flow aligns with the needs of the cell.

Other enzymes mentioned serve different functions within glycolysis: hexokinase initiates the pathway by phosphorylating glucose to glucose-6-phosphate, aldol