Question: why is pfk the rate limiting step?
Answer: Phosphofructokinase (PFK) is the enzyme that controls the third step of glycolysis, the conversion of fructose-6-phosphate (F6P) into fructose-1,6-biphosphate (F1,6BP). It works by transferring a phosphate group from ATP to F6P. This is the slowest reaction in glycolysis and therefore is the rate-limiting step.