Sandbox Reserved 1380
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{{Sandbox_Reserved_HLSC322}}<!-- PLEASE ADD YOUR CONTENT BELOW HERE --> | {{Sandbox_Reserved_HLSC322}}<!-- PLEASE ADD YOUR CONTENT BELOW HERE --> | ||
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== Function == | == Function == | ||
| - | + | A protein called <scene name=>hemoglobin</scene> (Hb), seen on the right, is eukaryotes' solution to transporting oxygen to our cells. These hemoglobin proteins are essential to our body as they serve as vehicles that transport oxygen across the body. In general, oxygen binds to hemoglobin in oxygen-rich areas like the lungs, and then the hemoglobin cleaves off in oxygen-poor areas such as the other cells across the body. Via this simple yet intricate mechanism, hemoglobin can supply oxygen to all cells. | |
| - | + | == Structural highlights == | |
| + | </StructureSection> | ||
| - | = | + | Hemoglobin comprises of four subunits, each having one polypeptide chain and one heme group. First, hemoglobin captures oxygen and transports it through the bloodstream by binding oxygen to each of its heme groups. These <scene name=>four heme groups</scene> are non-protein chemical compounds that are associated with hemoglobin and are necessary for its function. Each heme is a ring molecule made of C, N, O, and H with a single Fe2+ ion in the middle. Each heme is held in place within the monomer by a hydrophobic interactions and a covalent bond between the iron ion and a nitrogen atom in the side chain of what is termed the proximal histadine. Another histidine, termed the distal histadine, helps in oxygen binding by preventing oxidation of the iron atom (which would prevent oxygen from binding) and by preventing other molecules from binding. |
| - | + | When oxygen binds to the heme, a conformational change in the hemoglobin monomer takes place. The difference in conformation between the oxygenated and deoxygenated monomer turns out to be crucial for the function of hemoglobin. Thus, when one monomer in a deoxygenated hemoglobin molecule binds oxygen, that monomer’s conformation change forces a similar conformation change in the remaining three monomers, causing them to adopt a conformation more favorable to oxygen binding. This allows for accelerated binding and is known as cooperative binding. | |
| - | = | + | In terms of the second part of each subunit, the polypeptide chains of adult hemoglobin themselves are of two kinds, known as alpha and beta chains, similar in length but differing in amino acid sequence. Specially, the image shown is that of the delta chain in the beta chain. This is the <scene name='77/777700/D_chain_of_hemoglobin/1'>hemoglobin</scene>. |
| - | + | <StructureSection load='1fn3' size='350' side='right' caption='Hemoglobin: D-Chain''> | |
| - | + | The delta (HBD) and beta (HBB) genes are normally expressed in adultS; in particular, the two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin. Two alpha chains plus two delta chains constitute HbA2, which with HbF comprises the remaining 3% of adult hemoglobin. Five beta-like globin genes are found within a 45 kb cluster on chromosome 11 in the following order: 5' - epsilon – gamma-G – gamma-A – delta – beta - 3'. | |
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| + | == Disease == | ||
| + | An interesting phenomenon is that the heme group has the chemical and structural capabilities to capture an oxygen molecule as well as carbon monoxide molecule. The result is that carbon monoxide can also bind to the iron in the heme groups of hemoglobin, although the distal histidine helps prevent this. However, carbon monoxide binds to the heme with about 230 times the affinity of oxygen, thus, if both gases are available, carbon monoxide will outcompete oxygen for heme binding sites. Since CO is toxic, it is essential to have carbon monoxide detectors in our homes to alert us to high concentrations of this gas and prevent an uptake of CO rather than oxygen in our bodies. | ||
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| + | Another common and well-known disease is Sickle Cell Anemia in which the hemoglobin molecule sickles, leading to blockages in the capillaries. | ||
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| + | == Relevance == | ||
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 17:06, 1 March 2018
| This Sandbox is Reserved from January through July 31, 2018 for use in the course HLSC322: Principles of Genetics and Genomics taught by Genevieve Houston-Ludlam at the University of Maryland, College Park, USA. This reservation includes Sandbox Reserved 1311 through Sandbox Reserved 1430. |
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Function
A protein called (Hb), seen on the right, is eukaryotes' solution to transporting oxygen to our cells. These hemoglobin proteins are essential to our body as they serve as vehicles that transport oxygen across the body. In general, oxygen binds to hemoglobin in oxygen-rich areas like the lungs, and then the hemoglobin cleaves off in oxygen-poor areas such as the other cells across the body. Via this simple yet intricate mechanism, hemoglobin can supply oxygen to all cells.
Structural highlights
</StructureSection>
Hemoglobin comprises of four subunits, each having one polypeptide chain and one heme group. First, hemoglobin captures oxygen and transports it through the bloodstream by binding oxygen to each of its heme groups. These are non-protein chemical compounds that are associated with hemoglobin and are necessary for its function. Each heme is a ring molecule made of C, N, O, and H with a single Fe2+ ion in the middle. Each heme is held in place within the monomer by a hydrophobic interactions and a covalent bond between the iron ion and a nitrogen atom in the side chain of what is termed the proximal histadine. Another histidine, termed the distal histadine, helps in oxygen binding by preventing oxidation of the iron atom (which would prevent oxygen from binding) and by preventing other molecules from binding.
When oxygen binds to the heme, a conformational change in the hemoglobin monomer takes place. The difference in conformation between the oxygenated and deoxygenated monomer turns out to be crucial for the function of hemoglobin. Thus, when one monomer in a deoxygenated hemoglobin molecule binds oxygen, that monomer’s conformation change forces a similar conformation change in the remaining three monomers, causing them to adopt a conformation more favorable to oxygen binding. This allows for accelerated binding and is known as cooperative binding.
In terms of the second part of each subunit, the polypeptide chains of adult hemoglobin themselves are of two kinds, known as alpha and beta chains, similar in length but differing in amino acid sequence. Specially, the image shown is that of the delta chain in the beta chain. This is the .
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