Reversible and irreversible hemichrome generation by the oxygenation of nitrosylmyoglobin.
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.
Arnold
E V
EV
Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA.
Bohle
D S
DS
Jordan
P A
PA
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
D006420:Hemeproteins; D009211:Myoglobin; D009566:Nitrates; D009573:Nitrites; C001332:hemichrome; C031560:myoglobin nitroxide; D009569:Nitric Oxide; D010100:Oxygen