This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'All of the following enzymes are regulated by calcium or calmodulin, except \nSelect and explain. \nA. Adenylate cyclase, B. Glycogen synthase, C. Guanylyl cyclase, D. Hexokinase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ca2+ is needed for the direct activation of enzymes such as lipase (pancreatic), ATPase and succinate dehydrogenase. Calmodulin mediated action of Ca2+: Calmodulin is a calcium-binding regulatory protein. Ca-calmodulin complex activates ceain enzymes e.g. adenylate cyclase, Ca2+ dependent protein kinases, glycogen synthase, glycerol-3-phosphate dehydrogenase ref DM Vasudevan 8th ed page 492 box 34.2', 'role': 'assistant'}]