1j40: Difference between revisions
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|PDB= 1j40 |SIZE=350|CAPTION= <scene name='initialview01'>1j40</scene>, resolution 1.45Å | |PDB= 1j40 |SIZE=350|CAPTION= <scene name='initialview01'>1j40</scene>, resolution 1.45Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand= | |LIGAND= <scene name='pdbligand=2FU:BUT-2-ENEDIAL'>2FU</scene>, <scene name='pdbligand=CMO:CARBON+MONOXIDE'>CMO</scene>, <scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=HNI:PROTOPORPHYRIN+IX+CONTAINING+NI(II)'>HNI</scene> | ||
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1j3y|1J3Y]], [[1j3z|1J3Z]], [[1j41|1J41]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1j40 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1j40 OCA], [http://www.ebi.ac.uk/pdbsum/1j40 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1j40 RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
Human Hb, an alpha2beta2 tetrameric oxygen transport protein that switches from a T (tense) to an R (relaxed) quaternary structure during oxygenation, has long served as a model for studying protein allostery in general. Time-resolved spectroscopic measurements after photodissociation of CO-liganded Hb have played a central role in exploring both protein dynamical responses and molecular cooperativity, but the direct visualization and the structural consequences of photodeligation have not yet been reported. Here we present an x-ray study of structural changes induced by photodissociation of half-liganded T-state and fully liganded R-state human Hb at cryogenic temperatures (25-35 K). On photodissociation of CO, structural changes involving the heme and the F-helix are more marked in the alpha subunit than in the beta subunit, and more subtle in the R state than in the T state. Photodeligation causes a significant sliding motion of the T-state beta heme. Our results establish that the structural basis of the low affinity of the T state is radically different between the subunits, because of differences in the packing and chemical tension at the hemes. | Human Hb, an alpha2beta2 tetrameric oxygen transport protein that switches from a T (tense) to an R (relaxed) quaternary structure during oxygenation, has long served as a model for studying protein allostery in general. Time-resolved spectroscopic measurements after photodissociation of CO-liganded Hb have played a central role in exploring both protein dynamical responses and molecular cooperativity, but the direct visualization and the structural consequences of photodeligation have not yet been reported. Here we present an x-ray study of structural changes induced by photodissociation of half-liganded T-state and fully liganded R-state human Hb at cryogenic temperatures (25-35 K). On photodissociation of CO, structural changes involving the heme and the F-helix are more marked in the alpha subunit than in the beta subunit, and more subtle in the R state than in the T state. Photodeligation causes a significant sliding motion of the T-state beta heme. Our results establish that the structural basis of the low affinity of the T state is radically different between the subunits, because of differences in the packing and chemical tension at the hemes. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Shiro, Y.]] | [[Category: Shiro, Y.]] | ||
[[Category: Tame, J R.H.]] | [[Category: Tame, J R.H.]] | ||
[[Category: crystal photolysis]] | [[Category: crystal photolysis]] | ||
[[Category: riken structural genomics/proteomics initiative]] | [[Category: riken structural genomics/proteomics initiative]] | ||
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[[Category: tertiary structure change]] | [[Category: tertiary structure change]] | ||
''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 21:28:32 2008'' | ||