title: Extended X-ray absorption fine structure studies of Zn2Fe2 hybrid hemoglobins: absence of heme bond length changes in half-ligated species.
abstract: Metal hybrid hemoglobins, in which Zn(II) replaces Fe(II), have been structurally characterized by extended X-ray absorption structure (EXAFS) studies. Since Zn and Fe have very different K absorption edge energies, the structures of the ligated (Fe) and unligated (Zn) sites could be examined independently within a single molecule that mimics an intermediate ligation state. The observed EXAFS spectra and associated structural parameters are compared among the ligand free (alpha Zn)2(beta Zn)2, half-ligated (alpha FeCO)2(beta Zn)2 and (alpha Zn)2(beta FeCO)2, and fully ligated (alpha FeCO)2(beta FeCO)2 systems.
mesh_terms: D006418:Heme / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism*; D007501:Iron / Q000097:blood*; D008024:Ligands; D008433:Mathematics; D011487:Protein Conformation; D013057:Spectrum Analysis; D014965:X-Rays; D015032:Zinc / Q000097:blood*
chemical_list: D006454:Hemoglobins; D008024:Ligands; D006418:Heme; D007501:Iron; D015032:Zinc