This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glycogen Metabolism and Glycogen Storage, Subject name: Biochemistry
Which of the following is required for glycogen phosphorylase in glycogenolysis? 
Select and explain. 
A. Thiamine pyrophosphate, B. Pyridoxal phosphate, C. FAD, D. Citrate
B: Pyridoxal phosphate
Answer: B: Pyridoxal phosphate 
Explanation: Ans: B (Pyridoxal phosphate) Ref: Harper's Illustrated Biochemistry, 28th edition.Explanation:Glycogen phosphorylaseThis enzyme catalyzes the rate-limiting step in glvcogenolysis by releasing glucose-i- phosphate from the terminal alpha-1, 4- glycosidic bond.Glycogen phosphorylase has a pyridoxal phosphate (PLP. derived from Vitamin B6) at each catalytic site.