1gzx: Difference between revisions
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|PDB= 1gzx |SIZE=350|CAPTION= <scene name='initialview01'>1gzx</scene>, resolution 2.1Å | |PDB= 1gzx |SIZE=350|CAPTION= <scene name='initialview01'>1gzx</scene>, resolution 2.1Å | ||
|SITE= <scene name='pdbsite=HB1:O2+Binding+Site+For+Chain+D'>HB1</scene> | |SITE= <scene name='pdbsite=HB1:O2+Binding+Site+For+Chain+D'>HB1</scene> | ||
|LIGAND= <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene> | |LIGAND= <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=OXY:OXYGEN+MOLECULE'>OXY</scene> | ||
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY= | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1gzx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1gzx OCA], [http://www.ebi.ac.uk/pdbsum/1gzx PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1gzx RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
The cooperative binding of oxygen by haemoglobin results from restraints on ligand binding in the T state. The unfavourable interactions made by the ligands at the haems destabilise the T state and favour the high affinity R state. The T <==> R equilibrium leads, in the presence of a ligand, to a rapid increase in the R state population and therefore generates cooperative binding. There is now considerable understanding of this phenomenon, but the interactions that reduce ligand affinity in the T state have not yet been fully explored, owing to the difficulties in preparing T state haemoglobin crystals in which all the subunits are oxygenated. A protocol has been developed to oxygenate deoxy T state adult human haemoglobin (HbA) crystals in air at 4 C at all four haems without significant loss of crystalline order. The X-ray crystal structure, determined to 2.1 A spacing, shows significant changes in the alpha and beta haem pockets as well as changes at the alpha(1)beta(2) interface in the direction of the R quaternary structure. Most of the shifts and deviations from deoxy T state HbA are similar to, but larger than, those previously observed in the T state met and other partially liganded T state forms. They provide clear evidence of haem-haem interaction in the T state. | The cooperative binding of oxygen by haemoglobin results from restraints on ligand binding in the T state. The unfavourable interactions made by the ligands at the haems destabilise the T state and favour the high affinity R state. The T <==> R equilibrium leads, in the presence of a ligand, to a rapid increase in the R state population and therefore generates cooperative binding. There is now considerable understanding of this phenomenon, but the interactions that reduce ligand affinity in the T state have not yet been fully explored, owing to the difficulties in preparing T state haemoglobin crystals in which all the subunits are oxygenated. A protocol has been developed to oxygenate deoxy T state adult human haemoglobin (HbA) crystals in air at 4 C at all four haems without significant loss of crystalline order. The X-ray crystal structure, determined to 2.1 A spacing, shows significant changes in the alpha and beta haem pockets as well as changes at the alpha(1)beta(2) interface in the direction of the R quaternary structure. Most of the shifts and deviations from deoxy T state HbA are similar to, but larger than, those previously observed in the T state met and other partially liganded T state forms. They provide clear evidence of haem-haem interaction in the T state. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Tame, J.]] | [[Category: Tame, J.]] | ||
[[Category: Wilkinson, A.]] | [[Category: Wilkinson, A.]] | ||
[[Category: cooperativity]] | [[Category: cooperativity]] | ||
[[Category: haem protein]] | [[Category: haem protein]] | ||
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[[Category: transport]] | [[Category: transport]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 20:54:54 2008'' | ||