Sandbox GGC8

==Hemoglobin A==

<StructureSection load='1stp' size='340' side='right' caption='Caption for this structure' scene='78/781194/87_-58_his/1'>

<scene name='78/781194/Deoxy_human_hemoglobin_a/4'>DEOXY HUMAN HEMOGLOBIN A</scene>

Hemoglobin 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.<ref>doi:10.1007/s10533-009-9387-8</ref>

The 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).

Most of the understanding that of human physiology and pathology come from laboratory research that were performed on Hemoglobin<ref>doi: 10.1074/jbc.M109.066027</ref>

. Hemoglobin A is important for the body ;it helps the body to maintained a balanced amount of red blood cells.Low red blood cells in the body tissues can cause fatigue and weakness.

== Structural highlights ==

<scene name='78/781194/Hemoglobin/3'>The four Heme groups of Hemoglobin</scene>The hemoglobin molecule is composed of four polypeptide chains which are non covalently bound to each other . Each polypeptide chain consist of one Fe+ atom.<ref>doi: 10.1074/1BIJ.M109.066027</ref>

<scene name='78/781194/87_-58_his/8'>Proximal His87 and the distal His 58</scene>The 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.<ref>doi: 10.1074/jbc.M109.066027</ref>

<scene name='78/781194/92-63/5'>Proximal 92 His and distal 63 His</scene> 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<ref>doi: 10.1074/jbc.M109.066027</ref>

</StructureSection>

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