1jzm
From Proteopedia
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'''Crystal Structure of Scapharca inaequivalvis HbI, I114M Mutant in the Absence of ligand.''' | '''Crystal Structure of Scapharca inaequivalvis HbI, I114M Mutant in the Absence of ligand.''' | ||
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[[Category: Jr., W E.Royer.]] | [[Category: Jr., W E.Royer.]] | ||
[[Category: Knapp, J E.]] | [[Category: Knapp, J E.]] | ||
| - | [[Category: | + | [[Category: Allostery]] |
| - | [[Category: | + | [[Category: Cooperativity]] |
| - | [[Category: | + | [[Category: Heme protein]] |
| - | [[Category: | + | [[Category: Hemoglobin]] |
| - | [[Category: | + | [[Category: Invertebrate]] |
| - | [[Category: | + | [[Category: Oxygen-binding]] |
| - | [[Category: | + | [[Category: Oxygen-transport]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:07:01 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 19:07, 2 May 2008
Crystal Structure of Scapharca inaequivalvis HbI, I114M Mutant in the Absence of ligand.
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
1JZM is a Single protein structure of sequence from Scapharca inaequivalvis. 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 Page seeded by OCA on Fri May 2 22:07:01 2008
