title: Resonance Raman and EPR of nitrosyl human hemoglobin and chains, carp hemoglobin, and model compounds. Implications for the nitrosyl heme coordination state.
abstract: We report the joint resonance Raman (RR) and electron paramagnetic resonance (epr) study of five- and six-coordinate nitrosyl heme model compounds and of the titled nitrosyl hemoproteins. Both epr and RR spectra fall into two types which, in the models, correspond to five- and six-coordinate nitrosyl hemes. However, neither RR nor epr spectroscopy is highly sensitive to the nature of the bond between a nitrosyl heme and a coordinated nitrogenous base, nor do the results of one technique uniformly correlate with those of the other. It is not possible to use epr spectroscopy as a test for the coordination state of a nitrosyl heme. The position of the highest frequency (depolarized) RR band possibly provides such a test. Any breaking of the very weak bond between nitrosyl heme and proximal histidine in T state human HbNO is more a consequence of tertiary structural features unique to the human alphaNO chains than it is of properties of the T quaternary conformation.
mesh_terms: D000818:Animals; D002347:Carps; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme; D006454:Hemoglobins; D006801:Humans; D009603:Nitroso Compounds; D011487:Protein Conformation; D013045:Species Specificity; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman
chemical_list: D006454:Hemoglobins; D009603:Nitroso Compounds; D006418:Heme