FunctionHemoglobin A is an oxygen-transport protein. Hemoglobin is also an allosteric protein. It is a tetrameter composed of two types of sub units designated α and β, with stoichiometry α2β2 The function of Hemoglobin is to carry oxygen from the lungs to the other parts of the body . Hemoglobin also help to carry carbon dioxide through the blood cells.Hemoglobin A which is a component of the red blood cells also help with the transportation of carbon dioxide and hydrogen ions to the lungs. Hemoglobin proteins are capable of carrying four molecules of Oxygen . Hemoglobin also help red blood cells to maintain their disc like shape , which allows them to move freely through the blood vessels. Each sub-unit of Hemoglobin A contains a heme prosthetic group. The heme molecules give hemoglobin its red color.[1] DiseaseThe most well-known disease caused by mutation in the hemoglobin A protein is sickle-cell anemia. Sickle-cell anemia results from a mutation of the sixth residue in the β hemoglobin monomer from glutamic acid to a valine. This hemoglobin variant is termed 'hemoglobin S' (2hbs).
RelevanceMost of the understanding that of human physiology and pathology come from laboratory research that were performed on Hemoglobin. Structural highlightsProximal His87 and the distal His 58The α chain heme pocket with the relative orientation of the proximal Hisα87 and the distal Hisα58.proximal Hisα87(F8) is closer to the heme Fe atom by 0.10 Å more in the T-state compare to the R-state.[2] Proximal 92 His and distal 63 His The β chain heme pocket with the proximal Hisβ92(F8) and the distal Hisβ63(E7). In the R-state the proximal Hisβ92(F8) reorients itself to a more symmetric position relative to the heme molecule. In the T-state, the distal histidine E7 residue is positioned such that it partially blocks the oxygen-binding site. During the R → T transition, Hisβ63(E7) aligns itself with the heme Fe, and the Fe-His distances increase by a small but detectable amount[3]
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Crystal structure of Lysβ182-Lysβ282 crosslinked hemoglobin: A possible allosteric intermediate1 https://www.sciencedirect.com/science/article/pii/S0022283600935253?via%3Dihub#FIG4
https://www.verywellhealth.com/importance-of-hemoglobin-2249107
This page was last modified 05:08, 20 November 2019.