Bonding in HNO-myoglobin as characterized by X-ray absorption and resonance raman spectroscopies.
The EXAFS and resonance Raman spectra on the HNO-myoglobin adduct, 1, are consistent with the presence of HNO bound to a heme center. The three-dimensional structure about the heme center of 1 obtained from multiple-scattering (MS) analysis of the EXAFS of the heme protein yielded an Fe-N-O bond angle of 131 degrees and an Fe-N bond length of 1.82 A, which compare well with published values for model complexes containing RNO ligands. Resonance Raman spectra identified the nu(N=O) stretch at 1385 cm-1 (confirmed by 15N labeling), which corresponds well with those reported for small molecule HNO complexes. The wavelength of the nu(Fe-N) at 636 cm-1 of 1 is significantly higher than those of MbIINO and MbIIINO (554 and 595 cm-1, respectively). The XAFS, XANES, and resonance Raman data are all consistent with the structure deduced from the NMR experiments, providing more detail on the bonding between HNO and the metal center.
Immoos
Chad E
CE
Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
Sulc
Filip
F
Farmer
Patrick J
PJ
Czarnecki
Kazimierz
K
Bocian
David F
DF
Levina
Aviva
A
Aitken
Jade B
JB
Armstrong
Robert S
RS
Lay
Peter A
PA
D005583:Fourier Analysis; D008958:Models, Molecular; D009211:Myoglobin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry* / Q000378:metabolism; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman
D009211:Myoglobin; C031560:myoglobin nitroxide; D009569:Nitric Oxide