1ibe
From Proteopedia
(New page: 200px<br /> <applet load="1ibe" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ibe, resolution 1.8Å" /> '''DEOXY-HAEMOGLOBIN TR...) |
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| - | [[Image:1ibe. | + | [[Image:1ibe.jpg|left|200px]]<br /><applet load="1ibe" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1ibe" size=" | + | |
caption="1ibe, resolution 1.8Å" /> | caption="1ibe, resolution 1.8Å" /> | ||
'''DEOXY-HAEMOGLOBIN TRAPPED IN THE HIGH-AFFINITY (R) STATE'''<br /> | '''DEOXY-HAEMOGLOBIN TRAPPED IN THE HIGH-AFFINITY (R) STATE'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1IBE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Equus_caballus Equus caballus] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1IBE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Equus_caballus Equus caballus] with <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IBE OCA]. |
==Reference== | ==Reference== | ||
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[[Category: respiratory protein]] | [[Category: respiratory protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 16:00:36 2008'' |
Revision as of 14:00, 15 February 2008
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DEOXY-HAEMOGLOBIN TRAPPED IN THE HIGH-AFFINITY (R) STATE
Overview
Co-operative oxygen binding by the vertebrate haemoglobins arises from an, equilibrium between a quaternary structure with low affinity (T), favoured, in the absence of ligand, and a high affinity form (R) adopted by the, fully ligated protein. While R state haemoglobin has an oxygen affinity, close to that of isolated subunits, the affinity of the T state is roughly, 300-fold lower. The mechanism by which the T state restrains ligand, binding, and the pathway of the quaternary transition, have been largely, revealed by detailed crystallographic analyses of a number of haemoglobin, molecules in the equilibrium states, as well as intermediate forms of the, T state including partially ligated species. The ligation intermediates of, the R state, however, have not been as well characterized structurally. We, report here the crystal structure of one such intermediate species, namely, horse deoxyhaemoglobin in the R state, at 1.8 A resolution. While, ligand binding in the T state may result in unfavourable stereochemistry, in and around the haem-ligand complex, the more plastic R structure, appears to accommodate equally well both liganded and ligand-free haem., Loss of ligand at the R state haem results in movements of the haem and, shifts of the FG corners, which form characteristic intersubunit contacts, that distinguish the quaternary states. The shifts are comparable in, magnitude to the corresponding movements associated with de-ligation in, the T state, although they differ in direction. These and other, differences illustrate how the structural changes in the haem pocket are, communicated to the subunit interfaces and how the movements that can, occur in the R state may be impeded in the T state.
About this Structure
1IBE is a Protein complex structure of sequences from Equus caballus with as ligand. Full crystallographic information is available from OCA.
Reference
The crystal structure of horse deoxyhaemoglobin trapped in the high-affinity (R) state., Wilson J, Phillips K, Luisi B, J Mol Biol. 1996 Dec 13;264(4):743-56. PMID:8980683
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