title: Marked difference in the electronic structure of cyanide-ligated ferric protoglobins and myoglobin due to heme ruffling.
abstract: Electron paramagnetic resonance experiments reveal a significant difference between the principal g values (and hence ligand-field parameters) of the ferric cyanide-ligated form of different variants of the protoglobin of Methanosarcina acetivorans (MaPgb) and of horse heart myoglobin (hhMb). The largest principal g value of the ferric cyanide-ligated MaPgb variants is found to be significantly lower than for any of the other globins reported so far. This is at least partially caused by the strong heme distortions as proven by the determination of the hyperfine interaction of the heme nitrogens and mesoprotons. Furthermore, the experiments confirm recent theoretical predictions [Forti, F.; Boechi, L., Bikiel, D., Martí, M.A.; Nardini, M.; Bolognesi, M.; Viappiani, C.; Estrin, D.; Luque, F. J. J. Phys. Chem. B 2011, 115, 13771-13780] that Phe(G8)145 plays a crucial role in the ligand modulation in MaPgb. Finally, the influence of the N-terminal 20 amino-acid chain on the heme pocket in these protoglobins is also proven.
authors.affiliation: Department of Physics, University of Antwerp, B-2610 Antwerp, Belgium. sabine.vandoorslaer@ua.ac.be
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
authors.forename: Lesley
authors.initials: L
authors.lastname: Tilleman
authors.forename: Ben
authors.initials: B
authors.lastname: Verrept
authors.forename: Filip
authors.initials: F
authors.lastname: Desmet
authors.forename: Sara
authors.initials: S
authors.lastname: Maurelli
authors.forename: Florin
authors.initials: F
authors.lastname: Trandafir
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D004926:Escherichia coli / Q000235:genetics; D005292:Ferricyanides / Q000737:chemistry*; D005914:Globins / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D006736:Horses; D008024:Ligands; D017020:Methanosarcina / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D005292:Ferricyanides; D008024:Ligands; D009211:Myoglobin; D011994:Recombinant Proteins; C007931:hexacyanoferrate III; D006418:Heme; D010649:Phenylalanine; D005914:Globins