scholarly journals Some magnetic properties of Pseudomonas cytochrome oxidase

1979 ◽  
Vol 177 (1) ◽  
pp. 29-39 ◽  
Author(s):  
T A Walsh ◽  
M K Johnson ◽  
C Greenwood ◽  
D Barber ◽  
J P Springall ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Magnetic Circular Dichroism ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Parallel Study ◽  
Paramagnetic Resonance ◽  
Redox States ◽  
Electron Paramagnetic

The magnetic properties of the haem groups of Pseudomonas cytochrome oxidase and its cyanide-bound derivatives were studied in both the oxidized and reduced states by means of m.c.d. (magnetic circular dichroism) at low temperatures. In addition, the oxidized forms of the enzyme were also investigated by e.p.r. (electron-paramagnetic-resonance) spectroscopy, and a parallel study, using both e.p.r. and m.c.d., was made on Pseudomonas cytochrome c-551 to aid spectral assignments. For ascorbate-reduced Pseudomonas cytochrome oxidase, the temperature-independence of those features in the m.c.d. spectrum corresponding to the haem c, and the temperature-dependence of those signals corresponding to the haem d1, showed the former to be low-spin and the latter to be high-spin (s = 2). However, addition of cyanide to the reduced enzyme gave a form of the protein that was completely low-spin. The e.p.r. and m.c.d. sectra of oxidized Pseudomonas cytochrome oxidase and its cyanide derivative were consistent with the haem c and d1 components being low-spin in both cases. Pseudomonas cytochrome c-551 was found to be low-spin in both its oxidized and reduced redox states.

scholarly journals Azotobacter chroococcum 7Fe ferredoxin. Two pH-dependent forms of the reduced 3Fe clusters and its conversion to a 4Fe cluster

1984 ◽  
Vol 224 (1) ◽  
pp. 247-251 ◽  
Author(s):  
S J George ◽  
A J M Richards ◽  
A J Thomson ◽  
M G Yates
Keyword(s):  
Magnetic Circular Dichroism ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Iron Chelator ◽  
Anaerobic Treatment ◽  
Azotobacter Chroococcum ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
High Affinity ◽  
Ph Dependent ◽  
Electron Paramagnetic

Ferredoxin from Azotobacter chroococcum has been studied by low-temperature magnetic-circular-dichroism and electron-paramagnetic-resonance spectroscopy. When aerobically isolated ferredoxin contains a [3Fe-4S] and [4Fe-4S] cluster. Anaerobic treatment with dithionite in the presence of ethanediol reduces the [3Fe-4S] cluster to give two spectroscopically distinct forms RI and RII which are reversibly interconvertible with a pKa approximately 7.5. The higher-pH form, RII, has a high affinity for ferrous ion and converts readily to a [4Fe-4S]1+ cluster, scavenging iron from the medium. The presence of the iron chelator EDTA inhibits this conversion.

scholarly journals An antimycin A- and cyanide-resistant variant of Candida utilis arising during copper-limited growth

1973 ◽  
Vol 134 (4) ◽  
pp. 1051-1061 ◽  
Author(s):  
J. A. Downie ◽  
P. B. Garland
Keyword(s):  
Cytochrome Oxidase ◽  
Candida Utilis ◽  
Alternative Oxidase ◽  
Growth Parameters ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Limited Growth ◽  
Paramagnetic Resonance ◽  
Resistant Variant ◽  
Electron Paramagnetic

1. During copper-limited growth of Candida utilis in continuous culture on a non-fermentable carbon and energy source there is a selective pressure favouring the emergence of variants that are less dependent on copper. 2. We describe the properties of such a variant that by-passes cytochrome oxidase (EC 1.9.3.1) by utilizing an alternative oxidase communicating with the respiratory chain at about the level of cytochrome b. 3. Both direct studies of isolated mitochondria and calculations based on growth parameters showed that only one of the normal three phosphorylation sites was active. This site was localized between NADH and the cytochromes. 4. Growth of the variant with copper-supplemented media resulted in the return of cytochrome oxidase but not the loss of the alternative oxidase. 5. The alternative oxidase is inhibited by substituted benzhydroxamic acids. 6. Submitochondrial particles from the variant did not exhibit any novel electron-paramagnetic-resonance-spectroscopy features at about g=2.0 either at 80°K or 12°K.

scholarly journals Magnetic Properties of Bacterial Magnetosomes Produced by Magnetospirillum caucaseum SO-1

2021 ◽  
Vol 9 (9) ◽  
pp. 1854
Author(s):  
Kamil G. Gareev ◽  
Denis S. Grouzdev ◽  
Peter V. Kharitonskii ◽  
Demid A. Kirilenko ◽  
Andrei Kosterov ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Two Phase ◽  
Paramagnetic Resonance ◽  
Modified Method ◽  
Iron Oxide Magnetic Nanoparticles ◽  
A Minor ◽  
First Time ◽  
Electron Paramagnetic

In this study, the magnetic properties of magnetosomes isolated from lyophilized magnetotactic bacteria Magnetospirillum caucaseum SO-1 were assessed for the first time. The shape and size of magnetosomes and cell fragments were studied by electron microscopy and dynamic light scattering techniques. Phase and elemental composition were analyzed by X-ray and electron diffraction and Raman spectroscopy. Magnetic properties were studied using vibrating sample magnetometry and electron paramagnetic resonance spectroscopy. Theoretical analysis of the magnetic properties was carried out using the model of clusters of magnetostatically interacting two-phase particles and a modified method of moments for a system of dipole–dipole-interacting uniaxial particles. Magnetic properties were controlled mostly by random aggregates of magnetosomes, with a minor contribution from preserved magnetosome chains. Results confirmed the high chemical stability and homogeneity of bacterial magnetosomes in comparison to synthetic iron oxide magnetic nanoparticles.

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