Summary for 4SDH
| Entry DOI | 10.2210/pdb4sdh/pdb |
| Descriptor | HEMOGLOBIN I (DEOXY), PROTOPORPHYRIN IX CONTAINING FE (3 entities in total) |
| Functional Keywords | oxygen transport |
| Biological source | Scapharca inaequivalvis (ark clam) |
| Total number of polymer chains | 2 |
| Total formula weight | 33165.61 |
| Authors | Royerjunior, W.E. (deposition date: 1993-06-23, release date: 1993-10-31, Last modification date: 2024-02-28) |
| Primary citation | Royer Jr., W.E. High-resolution crystallographic analysis of a co-operative dimeric hemoglobin. J.Mol.Biol., 235:657-681, 1994 Cited by PubMed Abstract: 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. PubMed: 8289287DOI: 10.1006/jmbi.1994.1019 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.6 Å) |
Structure validation
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