This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Glutathione peroxidase contains the following metal ion: \nSelect and explain. \nA. Chromium, B. Manganese, C. Zinc, D. Selenium', 'role': 'user'}, {'content': "Answer: D \nExplanation: In red blood cells, the pentose phosphate pathway is the sole source of NADPH for the reduction of oxidized glutathione catalyzed by glutathione reductase, a flavoprotein containing FAD. Reduced glutathione removes H2O2 in a reaction catalyzed by glutathione peroxidase, an enzyme that contains the selenium analog of cysteine (selenocysteine) at the active site. Ref: Bender D.A., Mayes P.A. (2011). Chapter 21. The Pentose Phosphate Pathway & Other Pathways of Hexose Metabolism. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.", 'role': 'assistant'}]