Tutorial:How do we get the oxygen we breathe: Difference between revisions

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<StructureSection load='1hh0' size='500' side='right' caption='' scene='Hemoglobin/Foursubunits/5' >

=====Hemoglobin is a tetramer=====

In the three-dimensional structure of hemoglobin to the right, you see two <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_light_blue_chains/2'>light-blue chains</scene> and two <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_light_green_chains/1'>light-green chains</scene>. (''Drag the hemoglobin structure with the mouse to rotate it. To zoom, use your scroll-wheel, or drag while holding shift.'') These are the <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_four_monomers/1'>four monomers</scene> of the hemoglobin molecule, and they are shown in a cartoon-style representation where a single curved line connects the α-carbons in the amino acids of each chain and the [[secondary structure]] α-helices are shown as simplified cartoon helices. Because hemoglobin is composed of four monomers, it is called a <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_tetramer/2'>tetramer</scene>. The two types of monomers that make up the hemoglobin tetramer are distinguished by their color: the two α<scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_alpha_monomers/1'>-monomers</scene> in light-blue and the two β<scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/1hho_beta_monomers/1'>-monomers</scene> in light-green. Each α-monomer is a chain of 141 amino acids and each β-monomer is a chain of 146 amino acids. Be careful not to get confused with the context in which we use the label "α", or "alpha": remember that both the α- and the β-monomers contain α-carbons and α-helices. (''THINK'': How many amino acids does it take to build a molecule of hemoglobin?)

=====Each monomer has a heme group=====

Hemoglobin captures oxygen and transports it through the bloodstream by binding oxygen to each of its <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/Four_hemes/3'>four heme groups</scene>. These <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/One_heome/2'>heme groups</scene> are prosthetic groups; they are non-protein chemical compounds that are associated with hemoglobin and are necessary for its function. Each heme is <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/Heme_composition/1'>ring molecule made up of</scene> {{Template:ColorKey_Element_C}}arbon, {{Template:ColorKey_Element_N}}itrogen, {{Template:ColorKey_Element_O}}xygen and hydrogen, with a single <font color="#E06633">'''Fe²⁺'''</font> (iron) ion at its center, coordinated by the four surrounding nitrogens. Each heme is roughly <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/Planar_heme/1'>planar</scene>, and 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 <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/Proximal_histidine/1'>proximal histidine</scene>. Another histidine, termed the <scene name='User:Jaime_Prilusky/How_do_we_get_the_oxygen_we_breathe/Distal_histidine/2'>distal histidine</scene>, helps in oxygen binding by preventing oxidation of the iron atom (which would prevent oxygen from binding) and by preventing other molecules from binding.

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This page includes scenes, structures and ideas from [[User:Eric_Martz|Eric Martz]], [[User:Frieda S. Reichsman|Frieda S. Reichsman]]  and [[User:Angel_Herraez|Angel Herraez]].

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