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==The Structure Function Relationship of Haemoglobin== | ==The Structure Function Relationship of Haemoglobin== | ||
| - | {{55/559112/Oxyhb/1/55/559112/A_chain_haeme/1/1 }} | ||
| - | == Introduction == | ||
| + | == Introduction == | ||
| + | <Structure load='Oxyhaemoglobin.pdb' size='350' frame='true' align='right' caption='OxyHb'/> | ||
<scene name='55/559112/Oxyhb/1'>Haemoglobin</scene> is a tetrameric globular protein able to transport small molecules such as oxygen and carbon dioxide around the body to support life. Its a great example of how a protein's binding affinity to its ligand can change in response to changes in its environment. This is facilitated by small conformational changes that occur in and between subunits in a cooperative manner ultimately allowing O<sub>2</sub> to be picked up in the lungs and delivered to the tissues. | <scene name='55/559112/Oxyhb/1'>Haemoglobin</scene> is a tetrameric globular protein able to transport small molecules such as oxygen and carbon dioxide around the body to support life. Its a great example of how a protein's binding affinity to its ligand can change in response to changes in its environment. This is facilitated by small conformational changes that occur in and between subunits in a cooperative manner ultimately allowing O<sub>2</sub> to be picked up in the lungs and delivered to the tissues. | ||
Revision as of 09:42, 4 February 2015
The Structure Function Relationship of Haemoglobin
Introduction
|
is a tetrameric globular protein able to transport small molecules such as oxygen and carbon dioxide around the body to support life. Its a great example of how a protein's binding affinity to its ligand can change in response to changes in its environment. This is facilitated by small conformational changes that occur in and between subunits in a cooperative manner ultimately allowing O2 to be picked up in the lungs and delivered to the tissues.
Exploring the Structure
Haemoglobin (Hb) consists of 2 identical α subunits and 2 identical β subunits. The strongest inter-subunit interactions exist between the α and β subunits so Hb could be considered to be a dimer of α/β subunits. The α subunits have 141 residues while β subunits have 146 residues. Each monomer contains a haeme prosthetic group facilitating O2 coordination.
On the right is . Embedded in each monomer is the haeme prosthetic group with bound (ferrous) iron. Iron makes 6 coordination bonds. Four in the plane of the haeme to 4 nitrogens (blue); one to the proximal Histidine imidizole nitrogen and one reserved for oxygen.
The key to Hb's success is conformational changes which increase or decrease its affinity for O2. Hb exists in 2 main conformations, the relaxed, R-state (oxyHb) and the tense. T-state (deoxyHb). What factors induce this change in conformation? Hb exploits the changes in its environment, such as pH, CO2 and 2,3-BPG. These small molecules are called allosteric effectors because they bind to Hb at sites away from the O2 binding site and effect a change in conformation of Hb.
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Julie Langlois, Atena Farhangian, Rebecca Holstein, Elizabeth A. Dunlap, Katherine Reynolds, Elizeu Santos, Noam Gonen, Anna Lohning, Idan Ben-Nachum, Brian Ochoa, Shai Biran, Gauri Misra, Shira Weingarten-Gabbay, Keni Vidilaseris, Jamie Costa, Abhinav Mittal, Urs Leisinger, Madison Walberry, Edmond R Atalla, Brett M. Thumm, Brooke Fenn, Joel L. Sussman, Mati Cohen, Vesta Nwankwo, Dotan Shaniv, Gulalai Shah
