1cbm: Difference between revisions
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[[Image:1cbm.jpg|left|200px]] | [[Image:1cbm.jpg|left|200px]] | ||
'''THE 1.8 ANGSTROM STRUCTURE OF CARBONMONOXY-BETA4 HEMOGLOBIN: ANALYSIS OF A HOMOTETRAMER WITH THE R QUATERNARY STRUCTURE OF LIGANDED ALPHA2BETA2 HEMOGLOBIN''' | {{Structure | ||
|PDB= 1cbm |SIZE=350|CAPTION= <scene name='initialview01'>1cbm</scene>, resolution 1.74Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>, <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene> and <scene name='pdbligand=CMO:CARBON MONOXIDE'>CMO</scene> | |||
|ACTIVITY= | |||
|GENE= | |||
}} | |||
'''THE 1.8 ANGSTROM STRUCTURE OF CARBONMONOXY-BETA4 HEMOGLOBIN: ANALYSIS OF A HOMOTETRAMER WITH THE R QUATERNARY STRUCTURE OF LIGANDED ALPHA2BETA2 HEMOGLOBIN''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1CBM is a [ | 1CBM is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CBM OCA]. | ||
==Reference== | ==Reference== | ||
The 1.8 A structure of carbonmonoxy-beta 4 hemoglobin. Analysis of a homotetramer with the R quaternary structure of liganded alpha 2 beta 2 hemoglobin., Borgstahl GE, Rogers PH, Arnone A, J Mol Biol. 1994 Feb 25;236(3):817-30. PMID:[http:// | The 1.8 A structure of carbonmonoxy-beta 4 hemoglobin. Analysis of a homotetramer with the R quaternary structure of liganded alpha 2 beta 2 hemoglobin., Borgstahl GE, Rogers PH, Arnone A, J Mol Biol. 1994 Feb 25;236(3):817-30. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8114096 8114096] | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: oxygen transport]] | [[Category: oxygen transport]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:22:30 2008'' | ||
Revision as of 11:22, 20 March 2008
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| , resolution 1.74Å | |||||||
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| Ligands: | , and | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE 1.8 ANGSTROM STRUCTURE OF CARBONMONOXY-BETA4 HEMOGLOBIN: ANALYSIS OF A HOMOTETRAMER WITH THE R QUATERNARY STRUCTURE OF LIGANDED ALPHA2BETA2 HEMOGLOBIN
OverviewOverview
The beta-chains isolated from the human hemoglobin alpha 2 beta 2 heterotetramer self-assemble to form a beta 4 homotetramer. We report the structure of the carbonmonoxy-beta 4 (CO beta 4) tetramer refined at a resolution of 1.8 A. Compared to the three known quaternary structures of human hemoglobin, the T state, the R state and the R2 state, the quaternary structure of CO beta 4 most closely resembles the R state. While the degree of structural similarity between CO beta 4 and the R state of liganded alpha 2 beta 2 is quite high, differences between the alpha and beta-chain sequences result in interesting alternative packing arrangements at the subunit interfaces of CO beta 4. In particular, Arg40 beta and Asp99 beta interact across the CO beta 4 equivalent of the alpha 1 beta 2 interface to form two symmetry-related salt bridges that have no counterpart in either liganded or deoxyhemoglobin. Because these salt bridges are near a 2-fold symmetry axis, steric constraints prevent their simultaneous formation, and electron density images of Arg40 beta and Asp99 beta show equally populated dual conformations for the side-chains of both residues. Relative to the liganded alpha 2 beta 2 tetramer, the Arg40 beta...Asp99 beta salt bridges introduce ionic interactions that should strengthen the CO beta 4 tetramer. The CO beta 4 equivalent of the alpha 1 alpha 2 and beta 1 beta 2 interfaces strengthens the tetramer relative to the liganded alpha 2 beta 2 tetramer by tethering both ends of the central cavity. (The entrance to the central cavity is altered so that the N termini move closer together and the C termini further apart, forming an anion binding pocket that is absent in liganded alpha 2 beta 2 hemoglobin.) In contrast, analysis of the CO beta 4 counterpart of the alpha 1 beta 1 interface indicates that this interface is weakened in the CO beta 4 tetramer. These differences in interface stability provide a structural explanation for the published observation that the alpha 2 beta 2 tetramer assembles via a stable alpha 1 beta 1 dimer intermediate, whereas assembly of the CO beta 4 tetramer is characterized more accurately by a monomer-tetramer equilibrium.
DiseaseDisease
Known diseases associated with this structure: Erythremias, beta- OMIM:[141900], HPFH, deletion type OMIM:[141900], Heinz body anemias, beta- OMIM:[141900], Methemoglobinemias, beta- OMIM:[141900], Sickle cell anemia OMIM:[141900], Thalassemia-beta, dominant inclusion-body OMIM:[141900], Thalassemias, beta- OMIM:[141900]
About this StructureAbout this Structure
1CBM is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
The 1.8 A structure of carbonmonoxy-beta 4 hemoglobin. Analysis of a homotetramer with the R quaternary structure of liganded alpha 2 beta 2 hemoglobin., Borgstahl GE, Rogers PH, Arnone A, J Mol Biol. 1994 Feb 25;236(3):817-30. PMID:8114096
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