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Hemoglobin is an essential protein found in red blood cells that is responsible for carrying oxygen from the lungs to other bodily tissue, and transporting carbon dioxide from the tissue back to the lungs. Ever since the discovery of the relation between its structure and function by Max Perutz in 1978 after almost 20 years of research, hemoglobin has been the most thoroughly understood protein thus far. Figure 1: The molecule shown is a model of human deoxyhemoglobin A. It was created in RasMol version 2.6 by Roger Sayle. The 3D coordinates were determined from x-ray crystallography by Fermi, G., Perutz, M. F., Shaanan, B., Fourme, R.: The crystal structure of human deoxyhaemoglobin at 2.1 Angstroms resolution. J Mol Biol 175 pp. 159 (1984). Iron is displayed in blue and heme groups in red. Like other proteins, hemoglobin’s consists of many different structures, which help to define its function. The primary structure of hemoglobin is its amino acid sequence. There are 2 different chains, one alpha, containing 141 amino acids and one beta containing 146 amino acids. The protein sections of each of these chains are called a “globulin.” The secondary structure consists of each of the alpha and beta chains folding into 8 alpha- helical segments each with an alpha chain and a beta chain which, like all secondary structures are stabilized by hydrogen bonds.
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