title: Reversible and irreversible hemichrome generation by the oxygenation of nitrosylmyoglobin.
abstract: The repeated oxygenation/reduction/nitrosylation of nitrosylmyoglobin produces low-spin ferric heme hemichromes which have been characterized by electron spin resonance spectroscopy. The predominant myoglobin hemichrome is a chemically reversible dihistidyl complex identified by the g values 1.53, 2.21, and 2.97. Also present is a low-spin ferric hydroxide derivative which is represented by the g values 1.83, 2.18, and 2.59. The formation of these species goes undetected by UV-vis spectroscopy, but the oxygenation of myoglobin to metmyoglobin is correlated with complete conversion of nitric oxide to nitrate which is released following a clear induction period. These results are interpreted in terms of the intermediates generated during the MbNO oxygenation reaction.
authors: Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA.
authors: E V
authors: EV
authors: Arnold
authors: D S
authors: DS
authors: Bohle
authors: P A
authors: PA
authors: Jordan
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D006420:Hemeproteins / Q000737:chemistry*; D006736:Horses; D009211:Myoglobin / Q000031:analogs & derivatives* / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D011489:Protein Denaturation
chemical_list: D006420:Hemeproteins; D009211:Myoglobin; D009566:Nitrates; D009573:Nitrites; C001332:hemichrome; C031560:myoglobin nitroxide; D009569:Nitric Oxide; D010100:Oxygen