Hemoglobin: Difference between revisions
Eran Hodis (talk | contribs) No edit summary |
Eran Hodis (talk | contribs) No edit summary |
||
| Line 2: | Line 2: | ||
'''Hemoglobin''' is an oxygen-transport protein. Hemoglobin is an [[allosteric protein]]. It is a tetramer composed of two types of subunits designated α and β, whose stoichiometry is <scene name='Hemoglobin~Alpha2beta2~2'>α2β2</scene>. The | '''Hemoglobin''' is an oxygen-transport protein. Hemoglobin is an [[allosteric protein]]. It is a tetramer composed of two types of subunits designated α and β, whose stoichiometry is <scene name='Hemoglobin~Alpha2beta2~2'>α2β2</scene>. The | ||
<scene name='Hemoglobin~Foursubunits~1'>four subunits</scene> of hemoglobin sit roughly at the corners of a tetrahedron, facing each other across a <scene name='Hemoglobin~Cavity~ | <scene name='Hemoglobin~Foursubunits~1'>four subunits</scene> of hemoglobin sit roughly at the corners of a tetrahedron, facing each other across a <scene name='Hemoglobin~Cavity~6'>cavity</scene> at the center of the molecule. Each of the subunits <scene name='Hemoglobin~Bbsubunitswithheme~1'>contains a heme</scene> prosthetic group. The <scene name='Hemoglobin~4heme~1'>heme molecules</scene> give hemoglobin its red color. | ||
Each individual heme molecule contains one Fe2+ atom. In the lungs, where oxygen is abundant, an elemental oxygen molecule binds to the ferrous iron atom of the heme molecule and is later released in tissues needing oxygen. The heme group binds oxygen while still attached to the hemoglobin monomer. The spacefill view of the hemoglobin polypeptide subunit with an oxygenated heme group shows how the oxygenated heme group is held within the polypeptide. Anchoring of the heme is facilitated by a histidine nitrogen that binds to the iron. A second histidine is near the bound oxygen. the "arms" (propanoate groups) of heme face are hydrophilic and face the surface of the protein while the hydrophobic portions of the heme are buried among the hydrophobic amino acids of the protein. We can also view the anchored heme with the hemoglobin polypeptide subunit shown in a spacefill representation. | Each individual heme molecule contains one Fe2+ atom. In the lungs, where oxygen is abundant, an elemental oxygen molecule binds to the ferrous iron atom of the heme molecule and is later released in tissues needing oxygen. The heme group binds oxygen while still attached to the hemoglobin monomer. The spacefill view of the hemoglobin polypeptide subunit with an oxygenated heme group shows how the oxygenated heme group is held within the polypeptide. Anchoring of the heme is facilitated by a histidine nitrogen that binds to the iron. A second histidine is near the bound oxygen. the "arms" (propanoate groups) of heme face are hydrophilic and face the surface of the protein while the hydrophobic portions of the heme are buried among the hydrophobic amino acids of the protein. We can also view the anchored heme with the hemoglobin polypeptide subunit shown in a spacefill representation. | ||
Revision as of 19:48, 11 October 2007
|
Hemoglobin is an oxygen-transport protein. Hemoglobin is an allosteric protein. It is a tetramer composed of two types of subunits designated α and β, whose stoichiometry is . The of hemoglobin sit roughly at the corners of a tetrahedron, facing each other across a at the center of the molecule. Each of the subunits prosthetic group. The give hemoglobin its red color.
Each individual heme molecule contains one Fe2+ atom. In the lungs, where oxygen is abundant, an elemental oxygen molecule binds to the ferrous iron atom of the heme molecule and is later released in tissues needing oxygen. The heme group binds oxygen while still attached to the hemoglobin monomer. The spacefill view of the hemoglobin polypeptide subunit with an oxygenated heme group shows how the oxygenated heme group is held within the polypeptide. Anchoring of the heme is facilitated by a histidine nitrogen that binds to the iron. A second histidine is near the bound oxygen. the "arms" (propanoate groups) of heme face are hydrophilic and face the surface of the protein while the hydrophobic portions of the heme are buried among the hydrophobic amino acids of the protein. We can also view the anchored heme with the hemoglobin polypeptide subunit shown in a spacefill representation.