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Hemoglobin: Difference between revisions
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== Binding of ligands == | == Binding of ligands == | ||
With the binding of hemogloin for oxyen, the binding of oxygen is a cooperative process in the tetrameric form of normal adult hemoglobin. Therefore, unlike the normal hyperbolic curve, the oxygen binding curve of hemoglobin is sigmoidal, or 'S' shaped. | |||
However, when carbon dioxide is presented and it is at lower pH, Hemoglobin's affinity for oxygen is decreased. To give bicarbonate, Carbon dioxide reacts with water via the reaction: | |||
* CO<sub>2</sub> + H<sub>2</sub>O <-> HCO<sub>3</sub>- + H+ | |||
So blood with high carbon dioxide levels is also lower in pH. Hemoglobin can bind protons and carbon dioxide which causes a conformational change in the protein and facilitates the release of oxygen. Protons bind a various places along the protein and carbon dioxide binds at the alpha-amino group forming carbamate. Conversely, when the carbon dioxide levels in the blood decrease (i.e. around the lungs), carbon dioxide is released, increasing the oxygen affinity of the protein. This control of hemoglobin's affinity for oxygen by the binding and release of carbon dioxide is known as the Bohr effect. | |||
The binding of oxygen as well is affected by molecules such as 2,3-diphosphoglycerate, which lowers the affinity of hemoglobin for oxygen. In people acclimated to high altitudes, the concentration of 2,3-diphosphoglycerate in the blood is increased, which allows these individuals to deliver a larger amount of oxygen to tissues under conditions of lower oxygen tension. This phenomenon, where molecule Y affects the binding of molecule X to a transport molecule H, is called a heterotropic allosteric effect. | |||
== Types == | == Types == | ||
