Pitfalls in assigning heme axial coordination by EPR: c-Type cytochromes with atypical Met-His ligation

Different monohemic c-type cytochromes were analyzed by visible, EPR and 1H NMR spectroscopies. While the visible and NMR data show unambiguously that the heme iron has a Met-His heme axial coordination, the EPR data indicate an axial ligand field typical of that for a bis-histidinyl ligation. The v...

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Bibliographic Details
Published in:FEBS letters 1993-02, Vol.317 (3), p.233-236
Main Authors: Teixeira, Miguel, Campos, António P., Aguiar, António P., Costa, Helena S., Santos, Helena, Turner, David L., Xavier, António V.
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Axial ligand
Bacterial Proteins - chemistry
Biological and medical sciences
Cytochrome c Group - chemistry
Ectothiorhodospira halophila
Electron Spin Resonance Spectroscopy
EPR
Fundamental and applied biological sciences. Psychology
Heme - chemistry
Heme protein
Hemoproteins
Histidine
Ligand field
Magnetic Resonance Spectroscopy
Metalloproteins
Methionine
Methylobacterium extorquens
Methylophilus methylotrophus
NMR
Proteins
Spectrum Analysis
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Summary:Different monohemic c-type cytochromes were analyzed by visible, EPR and 1H NMR spectroscopies. While the visible and NMR data show unambiguously that the heme iron has a Met-His heme axial coordination, the EPR data indicate an axial ligand field typical of that for a bis-histidinyl ligation. The validity of the widely used EPR methods for the determination of the heme iron axial coordination, based on the crystal field parameters (tetragonality and rhombicity), is questioned.
ISSN:0014-5793
1873-3468
DOI:10.1016/0014-5793(93)81282-5