2hz2
From Proteopedia
(New page: 200px<br /> <applet load="2hz2" size="450" color="white" frame="true" align="right" spinBox="true" caption="2hz2, resolution 2.00Å" /> '''The x-ray crystal s...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:2hz2.gif|left|200px]]<br /> | + | [[Image:2hz2.gif|left|200px]]<br /><applet load="2hz2" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="2hz2" size=" | + | |
caption="2hz2, resolution 2.00Å" /> | caption="2hz2, resolution 2.00Å" /> | ||
'''The x-ray crystal structure of ferric Synechocystis hemoglobin H117A mutant with a covalent linkage'''<br /> | '''The x-ray crystal structure of ferric Synechocystis hemoglobin H117A mutant with a covalent linkage'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Synechocystis hemoglobin contains an unprecedented covalent bond between a | + | Synechocystis hemoglobin contains an unprecedented covalent bond between a nonaxial histidine side chain (H117) and the heme 2-vinyl. This bond has been previously shown to stabilize the ferric protein against denaturation, and also to affect the kinetics of cyanide association. However, it is unclear why Synechocystis hemoglobin would require the additional degree of stabilization accompanying the His117-heme 2-vinyl bond because it also displays endogenous bis-histidyl axial heme coordination, which should greatly assist heme retention. Furthermore, the mechanism by which the His117-heme 2-vinyl bond affects ligand binding has not been reported, nor has any investigation of the role of this bond on the structure and function of the protein in the ferrous oxidation state. Here we report an investigation of the role of the Synechocystis hemoglobin His117-heme 2-vinyl bond on structure, heme coordination, exogenous ligand binding, and stability in both the ferrous and ferric oxidation states. Our results reveal that hexacoordinate Synechocystis hemoglobin lacking this bond is less stable in the ferrous oxidation state than the ferric, which is surprising in light of our understanding of pentacoordinate Hb stability, in which the ferric protein is always less stable. It is also demonstrated that removal of the His117-heme 2-vinyl bond increases the affinity constant for intramolecular histidine coordination in the ferric oxidation state, thus presenting greater competition for the ligand binding site and lowering the observed rate and affinity constants for exogenous ligands. |
==About this Structure== | ==About this Structure== | ||
| - | 2HZ2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with CD, SO4 and HEM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 2HZ2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with <scene name='pdbligand=CD:'>CD</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HZ2 OCA]. |
==Reference== | ==Reference== | ||
| Line 14: | Line 13: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Synechocystis sp.]] | [[Category: Synechocystis sp.]] | ||
| - | [[Category: Hoy, J | + | [[Category: Hoy, J A.]] |
[[Category: CD]] | [[Category: CD]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
| Line 26: | Line 25: | ||
[[Category: synechocystis]] | [[Category: synechocystis]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:47:19 2008'' |
Revision as of 15:47, 21 February 2008
|
The x-ray crystal structure of ferric Synechocystis hemoglobin H117A mutant with a covalent linkage
Overview
Synechocystis hemoglobin contains an unprecedented covalent bond between a nonaxial histidine side chain (H117) and the heme 2-vinyl. This bond has been previously shown to stabilize the ferric protein against denaturation, and also to affect the kinetics of cyanide association. However, it is unclear why Synechocystis hemoglobin would require the additional degree of stabilization accompanying the His117-heme 2-vinyl bond because it also displays endogenous bis-histidyl axial heme coordination, which should greatly assist heme retention. Furthermore, the mechanism by which the His117-heme 2-vinyl bond affects ligand binding has not been reported, nor has any investigation of the role of this bond on the structure and function of the protein in the ferrous oxidation state. Here we report an investigation of the role of the Synechocystis hemoglobin His117-heme 2-vinyl bond on structure, heme coordination, exogenous ligand binding, and stability in both the ferrous and ferric oxidation states. Our results reveal that hexacoordinate Synechocystis hemoglobin lacking this bond is less stable in the ferrous oxidation state than the ferric, which is surprising in light of our understanding of pentacoordinate Hb stability, in which the ferric protein is always less stable. It is also demonstrated that removal of the His117-heme 2-vinyl bond increases the affinity constant for intramolecular histidine coordination in the ferric oxidation state, thus presenting greater competition for the ligand binding site and lowering the observed rate and affinity constants for exogenous ligands.
About this Structure
2HZ2 is a Single protein structure of sequence from Synechocystis sp. with , and as ligands. Full crystallographic information is available from OCA.
Reference
Covalent heme attachment in Synechocystis hemoglobin is required to prevent ferrous heme dissociation., Hoy JA, Smagghe BJ, Halder P, Hargrove MS, Protein Sci. 2007 Feb;16(2):250-60. PMID:17242429
Page seeded by OCA on Thu Feb 21 17:47:19 2008
Categories: Single protein | Synechocystis sp. | Hoy, J A. | CD | HEM | SO4 | Covalent heme vinyl link | Ferric | Globin | Heme | Hemoglobin | Hexacoordinate | Synechocystis
