4sdh

HIGH RESOLUTION CRYSTALLOGRAPHIC ANALYSIS OF A COOPERATIVE DIMERIC HEMOGLOBIN

spinqualitylabelsall models 4sdh, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4sdh is a 2 chain structure with sequence from Scapharca inaequivalvis. This structure supersedes the now removed PDB entry 2sdh. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HEM Resources: FirstGlance, OCA, RCSB, PDBsum 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 High-resolution crystal structures of the co-operative dimeric hemoglobin from the blood clam Scapharca inaequivalvis have been determined in the unliganded (deoxy) and carbon monoxide (CO) liganded states. The deoxy structure has been refined at 1.6 A resolution to an R-factor of 0.158 and the CO structure has been refined at 1.4 A resolution to an R-factor of 0.159. These structures reveal details of the structural transitions involved in co-operative ligand binding that involve only a minor rotation of subunits but very striking tertiary changes at the interface. A small number of residues in the F-helix appear to mediate co-operativity in this simple hemoglobin. The oxygen affinity of each subunit appears to be largely dictated by the disposition of phenylalanine 97, whose side-chain packs in the heme pocket in the deoxy state but is extruded towards the interface in the CO-liganded structure. Direct involvement of the ligand-binding heme group is a novel feature of the subunit interface and appears important for intersubunit communication. Ligation alters the conformation of the heme propionate groups along with two interacting residues from the symmetry-related subunit. These two residues, lysine 96 and asparagine 100, link the heme of one subunit with the F-helix of the second subunit in such a way as to influence the ligand affinity of that subunit. The interface is highly hydrated by well-ordered water molecules that are likely to be important in the stabilization of the two structures. High-resolution crystallographic analysis of a co-operative dimeric hemoglobin.,Royer WE Jr J Mol Biol. 1994 Jan 14;235(2):657-81. PMID:8289287 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Hemoglobin 3D structures

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