Hemoglobin consistsmostly of protein subunits (the "globin" chains), and these proteins, in turn, are folded chains of a large number of different amino acids...
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HemoglobinFrom Wikipedia, the free encyclopediaHemoglobin, human, adult(heterotetramer, (αβ)2)Structure of human hemoglobin. The proteins'αandβsubunits are in red and blue, and the iron-containinghemegroups in green. FromPDB1GZXProteopediaHemoglobin