2hz2 | pdb_00002hz2

The x-ray crystal structure of ferric Synechocystis hemoglobin H117A mutant with a covalent linkage

spinqualitylabelsall models 2hz2, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2hz2 is a 1 chain structure with sequence from Aphanocapsa sp. (strain n-1). Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CD, HEM, SO4 Related: 2hz1, 2hz3, 1rtx Gene: glbN (Aphanocapsa sp. (strain N-1)) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [TRHBN_SYNY3] Forms a very stable complex with oxygen. The oxygen dissociation rate is 0.011 s(-1). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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