Bioinorganic Chemistry: Hemoglobin and Oxygen Binding

Hemoglobin contains an iron(II)-porphyrin center responsible for O2 transport. (a) Describe the coordination environment of Fe(II) in deoxyhemoglobin vs. oxyhemoglobin. (b) Explain the molecular basis of cooperative oxygen binding (the Hill coefficient). (c) How does 2,3-bisphosphoglycerate (2,3-BPG) affect O2 affinity? (d) Why does CO bind to hemoglobin ~200× more strongly than O2, and what are the structural consequences? (e) Calculate the fractional saturation (Y) when pO2 = 40 torr, given P50 = 26 torr and n = 2.8.