1jzl
From Proteopedia
(New page: 200px<br /> <applet load="1jzl" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jzl, resolution 1.50Å" /> '''Crystal structure o...) |
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| - | [[Image:1jzl.gif|left|200px]]<br /> | + | [[Image:1jzl.gif|left|200px]]<br /><applet load="1jzl" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1jzl" size=" | + | |
caption="1jzl, resolution 1.50Å" /> | caption="1jzl, resolution 1.50Å" /> | ||
'''Crystal structure of Sapharca inaequivalvis HbI, I114M mutant ligated to carbon monoxide.'''<br /> | '''Crystal structure of Sapharca inaequivalvis HbI, I114M mutant ligated to carbon monoxide.'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Cooperative ligand binding in the dimeric hemoglobin from the blood clam | + | Cooperative ligand binding in the dimeric hemoglobin from the blood clam Scapharca inaequivalvis results primarily from tertiary, rather than quaternary, structural changes. Ligand binding is coupled with conformational changes of key residues, including Phe 97, which is extruded from the proximal heme pocket, and the heme group, which moves deeper into the heme pocket. We have tested the role of the heme movement in cooperative function by mutating Ile 114, at the base of the heme pocket. Replacement of this residue with a Met did not disturb the hemoglobin structure or significantly alter equilibrium ligand binding properties. In contrast, substitution with a Phe at position 114 inhibits the ligand-linked movement of the heme group, and substantially reduces oxygen affinity and cooperativity. As the extent of heme movement to the normal position of the ligated state is diminished, Phe 97 is inhibited from its movement into the interface upon ligand binding. These results indicate a tight coupling between these two key cooperative transitions and suggest that the heme movement may be an obligatory trigger for expulsion of Phe 97 from the heme pocket. |
==About this Structure== | ==About this Structure== | ||
| - | 1JZL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Scapharca_inaequivalvis Scapharca inaequivalvis] with HEM and CMO as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1JZL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Scapharca_inaequivalvis Scapharca inaequivalvis] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=CMO:'>CMO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1JZL OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Cushing, L.]] | [[Category: Cushing, L.]] | ||
| - | [[Category: Gibson, Q | + | [[Category: Gibson, Q H.]] |
| - | [[Category: Jr., W | + | [[Category: Jr., W E.Royer.]] |
| - | [[Category: Knapp, J | + | [[Category: Knapp, J E.]] |
[[Category: CMO]] | [[Category: CMO]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
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[[Category: oxygen-transport]] | [[Category: oxygen-transport]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:28:37 2008'' |
Revision as of 11:28, 21 February 2008
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Crystal structure of Sapharca inaequivalvis HbI, I114M mutant ligated to carbon monoxide.
Overview
Cooperative ligand binding in the dimeric hemoglobin from the blood clam Scapharca inaequivalvis results primarily from tertiary, rather than quaternary, structural changes. Ligand binding is coupled with conformational changes of key residues, including Phe 97, which is extruded from the proximal heme pocket, and the heme group, which moves deeper into the heme pocket. We have tested the role of the heme movement in cooperative function by mutating Ile 114, at the base of the heme pocket. Replacement of this residue with a Met did not disturb the hemoglobin structure or significantly alter equilibrium ligand binding properties. In contrast, substitution with a Phe at position 114 inhibits the ligand-linked movement of the heme group, and substantially reduces oxygen affinity and cooperativity. As the extent of heme movement to the normal position of the ligated state is diminished, Phe 97 is inhibited from its movement into the interface upon ligand binding. These results indicate a tight coupling between these two key cooperative transitions and suggest that the heme movement may be an obligatory trigger for expulsion of Phe 97 from the heme pocket.
About this Structure
1JZL is a Single protein structure of sequence from Scapharca inaequivalvis with and as ligands. Full crystallographic information is available from OCA.
Reference
Restricting the ligand-linked heme movement in Scapharca dimeric hemoglobin reveals tight coupling between distal and proximal contributions to cooperativity., Knapp JE, Gibson QH, Cushing L, Royer WE Jr, Biochemistry. 2001 Dec 11;40(49):14795-805. PMID:11732898
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