What is the rate-limiting enzyme in glycolysisGroup of answer choicesphosphofructokinasecreatine kinasehexokinasepyruvate kinase

Rate-Limiting Enzyme in Glycolysis

The rate-limiting enzyme is the one that regulates the pace of the entire glycolytic pathway. In glycolysis, the key regulatory step is the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, which is catalyzed by the enzyme phosphofructokinase (PFK). This step is crucial because it is highly regulated by the energy state of the cell and the availability of substrates.

1. Phosphofructokinase (PFK): It is the primary rate-limiting enzyme in glycolysis. It is allosterically inhibited by ATP (indicating high energy levels) and activated by AMP (indicating low energy levels), making it essential for regulating glycolysis based on the energy needs of the cell.

2. Creatine Kinase: This enzyme is involved in the ATP regeneration process in muscle cells but is not involved in glycolysis.

3. Hexokinase: While it is the first enzyme in the glycolytic pathway, it is not considered the rate-limiting step because it is not as tightly regulated as PFK.

4. Pyruvate Kinase: This enzyme catalyzes the final step of glycolysis, but it also does not serve as the rate-limiting enzyme.

Final Answer

Phosphofructokinase is the rate-limiting enzyme in glycolysis.