EPR studies on the photoinduced intermediates of NO complexes in recombinant ferric-Mb trapped at low temperatures
| Autor: | Masao Ikeda-Saito, Hiroshi Hori, Futoshi Masuya, Yi Dou |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
inorganic chemicals
Steric effects Models Molecular Photochemistry Ligands Nitric Oxide Biochemistry law.invention Inorganic Chemistry chemistry.chemical_compound law Side chain medicine Animals Humans Point Mutation Electron paramagnetic resonance Heme chemistry.chemical_classification Photolysis Photodissociation Electron Spin Resonance Spectroscopy Temperature Recombinant Proteins Amino acid chemistry Myoglobin Ferric Metmyoglobin medicine.drug |
| Zdroj: | Journal of inorganic biochemistry. 82(1-4) |
| ISSN: | 0162-0134 |
| Popis: | The nitrosyl complex of ferric myoglobin is EPR-silent. Upon photolysis at low temperatures, the photoinduced intermediates trapped in the distal heme cavity exhibit new EPR spectra due to the interaction between the photodissociated NO (S=1/2) and the ferric high spin heme (S=5/2). In order to elucidate the effect of distal E7 (His64) and E11 (Val68) mutations upon the electronic structure of the metal center, its immediate environment, and its interaction with the photodissociated NO, EPR spectra of the photoproducts of the NO complexes of recombinant ferric Mb mutants were measured at 5 K. EPR spectra of the photoproducts were closely related to the size and/or the polarity of the distal pocket residues. The distal pocket of the E7 mutants seemed to be sterically crowded, even decreasing the side chain volume or changing its hydrophobicity by replacing amino acid at position 64. We have found that the mobility of the photodissociated NO molecule in the distal heme pocket was strongly governed by the nature of the amino acid residue at E11 position. |
| Databáze: | OpenAIRE |
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