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Hemoglobin: Difference between revisions
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[[File:Hemoglobin2.png|left|250px|thumb|Hemoglobin structure.]] | [[File:Hemoglobin2.png|left|250px|thumb|Hemoglobin structure.]] | ||
A porphyrin, known as a heterocyclic ring, is located at the center of the molecule and has an iron atom, which helps oxygens begin binding. An iron that consists porphyrin is called a heme. It is also part of the prosthetic group of hemoglobin, myoglobin, and the cytochromes. <ref> [http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/heme.htm Synthesis of Heme] Joyce J. Diwan. Biochemistry of Metabolism </ref> Globin is the protein that protects the heme molecule from any other dangers. It is also called a globular protein. A single unit of hemoglobin includes a heme that is attached to a globular protein. <ref name=bioche> [http://themedicalbiochemistrypage.org/hemoglobin-myoglobin.html Hemoglobin and Myoglobin ] Michael W. King. The Medical Biochemistry Page </ref> Hemoglobin synthesis requires the collaboration of heme and globin. In the mitochondria and the cytosol of immature red blood cells, the heme part is combined with a series of steps. On the other hand, the globin protein parts are incorporated with ribosomes in the cytosol. From the proerythroblast to the reticulocyte in the bone marrow, they keep producing hemoglobins in the cell. The nucleus is then removed from mammalian red blood cells. This happens only in humans but not in other species. Although the nucleus is disappeared in red blood cells, residual ribosomal RNA keeps combining and producing hemoglobin until the reticulocyte loses its RNA as soon as it enters the vasculature. | A porphyrin, known as a heterocyclic ring, is located at the center of the molecule and has an iron atom, which helps oxygens begin binding. An iron that consists porphyrin is called a heme. It is also part of the prosthetic group of hemoglobin, myoglobin, and the cytochromes. <ref> [http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/heme.htm Synthesis of Heme] Joyce J. Diwan. Biochemistry of Metabolism </ref> Globin is the protein that protects the heme molecule from any other dangers. It is also called a globular protein. A single unit of hemoglobin includes a heme that is attached to a globular protein. <ref name=bioche> [http://themedicalbiochemistrypage.org/hemoglobin-myoglobin.html Hemoglobin and Myoglobin ] Michael W. King. The Medical Biochemistry Page </ref> Hemoglobin synthesis requires the collaboration of heme and globin. In the mitochondria and the [[cytosol]] of immature red blood cells, the heme part is combined with a series of steps. On the other hand, the globin protein parts are incorporated with ribosomes in the cytosol. From the proerythroblast to the reticulocyte in the bone marrow, they keep producing hemoglobins in the cell. The nucleus is then removed from mammalian red blood cells. This happens only in humans but not in other species. Although the nucleus is disappeared in red blood cells, residual ribosomal RNA keeps combining and producing hemoglobin until the reticulocyte loses its RNA as soon as it enters the vasculature. | ||
In adult humans, hemoglobin is a tetramer, which has two alpha and two beta subunits. The subunits are identical in structure and have equal size. Each subunit has a molecular weight of 16,000 grams. Therefore, a total molecular weight is about 64,000 grams. Since each subunit of hemoglobin includes a single heme, as we aleardy discuss that a heme consists of four different molecules, adult human hemoglobin has a toatla binding capacity of four oxygen molecules. <ref name=bioche/> | In adult humans, hemoglobin is a tetramer, which has two alpha and two beta subunits. The subunits are identical in structure and have equal size. Each subunit has a molecular weight of 16,000 grams. Therefore, a total molecular weight is about 64,000 grams. Since each subunit of hemoglobin includes a single heme, as we aleardy discuss that a heme consists of four different molecules, adult human hemoglobin has a toatla binding capacity of four oxygen molecules. <ref name=bioche/> | ||
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== Binding of ligands == | == Binding of ligands == | ||
Besides the binding of | Besides the binding of hemoglobin for oxygen, the binding of oxygen is also an essential process in the tetrameric form of normal adult hemoglobin. Unlike the normal hyperbolic curve, the oxygen binding curve of hemoglobin is sigmoidal, or 'S' shaped. | ||
However, when carbon dioxide is present and it is at a lower pH level, Hemoglobin's connection to oxygen is decreasing. To get bicarbonate, Carbon dioxide needs to react with water through the reaction: | However, when carbon dioxide is present and it is at a lower pH level, Hemoglobin's connection to oxygen is decreasing. To get bicarbonate, Carbon dioxide needs to react with water through the reaction: | ||
