1H NMR studies of paramagnetic ferricytochrome c-551 from Pseudomonas aeruginosa at high pH: The role of histidine 16 in the spin transition
| Autor: | José M. Moratal, Hermas R. Jiménez, Cristina Pardal |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
chemistry.chemical_classification
Cytochrome biology Spin transition Analytical chemistry Inorganic Chemistry chemistry.chemical_compound Crystallography Deprotonation chemistry Spin crossover Materials Chemistry Metalloprotein biology.protein Proton NMR Physical and Theoretical Chemistry Heme Two-dimensional nuclear magnetic resonance spectroscopy |
| Zdroj: | Polyhedron. 24:1813-1820 |
| ISSN: | 0277-5387 |
| DOI: | 10.1016/j.poly.2005.06.007 |
| Popis: | Cytochrome c-551 from the mesophile Pseudomonas aeruginosa is an electronic transfer protein that contains 82 amino-acid residues and a c-type heme as the prosthetic group with low spin Fe(II) in the reduced form and low spin Fe(III) in the oxidized form of cytochrome c-551. We have studied the electronic properties of ferricytochrome c-551 from P. aeruginosa at high pH (9–11.4) by means of paramagnetic 1H NMR spectra and the T1 and T2 values of isotropically shifted proton resonances. We have also analyzed the temperature dependence of the hyperfine-shifts. Resonance assignment of some signals was based on 2D saturation transfer experiments, EXSY. These results indicate the existence of high-spin iron(III) cytochrome c-551 (S = 5/2, 6A1) with penta or hexacoordinated symmetry at high pH. A spin transition from low-spin iron(III) to high-spin iron(III) has been produced. This transition can be associated with the deprotonation of the axially coordinated amino-acid to iron, His-16. We also discuss the spin crossover between different ferricytochromes c. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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