title: Spin Crossover in Nitrito-Myoglobin as Revealed by Resonance Raman Spectroscopy.
abstract: The myoglobin (Mb) heme Fe-O-N=O and heme Fe-O-N=O/2-nitrovinyl species have been characterized by resonance Raman spectroscopy. In the heme Fe-O-N=O species, the bound nitrite ligand is removed by solvent exchange, thus reforming metmyoglobin (metMb). The high-spin heme Fe-O-N=O unit is converted into a low-spin heme Fe-O-N=O/2-nitrovinyl species that can be reversibly switched between a low- and a high-spin state without removing the bound nitrite ligand, as observed in the case of the heme Fe-O-N=O species. This spin-state change is likely to be accompanied by a general structural rearrangement in the protein-binding pocket. This example is the first of a globin protein that can reversibly change its metal spin state through an internal perturbation. These findings provide a basis for understanding the structure-function relationship of the spin cross found in other metalloenzymes and Fe(III) -porphyrin complexes.
authors.affiliation: Department of Chemistry, University of Cyprus, PO Box 20537, 1678, Nicosia, Cyprus.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Lambrou
authors.affiliation: Department of Chemistry, University of Cyprus, PO Box 20537, 1678, Nicosia, Cyprus.
authors.forename: Androulla
authors.initials: A
authors.lastname: Ioannou
authors.affiliation: Department of Chemistry, University of Cyprus, PO Box 20537, 1678, Nicosia, Cyprus. effiep@ucy.ac.cy.
authors.forename: Eftychia
authors.initials: E
authors.lastname: Pinakoulaki
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D008024:Ligands; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011485:Protein Binding; D013059:Spectrum Analysis, Raman
chemical_list: D005290:Ferric Compounds; D008024:Ligands; D009211:Myoglobin; D009573:Nitrites; D011166:Porphyrins; C069808:heme O; D006418:Heme
keywords: Raman spectroscopy; heme proteins; nitrite ligands; spin crossover