This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Rate limiting enzyme in glycolysis 
Select and explain. 
A. Phosphofructokinase, B. Glucose 6 dehydrogenase, C. Pyruvate kinase, D. Pyruvate carboxylase
A: Phosphofructokinase
Answer: A: Phosphofructokinase 
Explanation: Fructose-6-phosphate is fuher phosphorylated to fructose1,6 bisphosphate. The enzyme is phosphofructokinase. is the rate-limiting enzyme of glycolysis. It is an allosterically regulated enzyme catalyzes the second phosphorylation step of glycolysis using a second molecule of ATP is an impoant key enzyme of this pathwayRef: DM Vasudevan, 7th edition, page no: 109