Electronic structure of various ferricenium systems as inferred from Raman, infrared, low-temperature electronic absorption, and electron paramagnetic resonance measurements

1975 ◽  
Vol 14 (5) ◽  
pp. 955-970 ◽  
Author(s):  
D. Michael. Duggan ◽  
David N. Hendrickson
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electronic Structure ◽  
Low Temperature ◽  
Electronic Absorption ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Electron Paramagnetic Resonance in Spinach Chloroplasts at Low Temperature

Nature ◽  
1964 ◽  
Vol 204 (4963) ◽  
pp. 1076-1078 ◽  
Author(s):  
POWER SOGO ◽  
RUSSELL FAUCETT ◽  
THOMAS HOLZER
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Low Temperature ◽  
Paramagnetic Resonance ◽  
Spinach Chloroplasts ◽  
Electron Paramagnetic

Free radical metabolites in myocardium during ischemia and reperfusion

1991 ◽  
Vol 261 (4) ◽  
pp. L81-L86 ◽  
Author(s):  
Enno K. Ruuge ◽  
Alexander N. Ledenev ◽  
Vladimir L. Lakomkin ◽  
Alexander A. Konstantinov ◽  
Marina Yu. Ksenzenko
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radical ◽  
Low Temperature ◽  
Coenzyme Q ◽  
Heart Tissue ◽  
Paramagnetic Species ◽  
Spectral Parameters ◽  
Paramagnetic Resonance ◽  
Oxygen Paradox ◽  
Electron Paramagnetic

Low-temperature electron paramagnetic resonance (EPR) spectroscopy and spin traps were used to measure paramagnetic species generation in rat hearts and isolated mitochondria. The hearts were freeze-clamped at 77 K during control perfusion by the Langendorff procedure, after 20–30 min of normothermic ischemia or 10–30 s of reperfusion with oxygenated perfusate. All EPR spectra measured at 4.5–50 K exhibited signals of both mitochondrial free radical centers and FeS proteins. The analysis of spectral parameters measured at 243 K showed that free radicals in heart tissue were semiquinones of coenzyme Q10 and flavins. The appearance of a typical “doublet” signal at g = 1.99 in low-temperature spectra indicated that a part of ubisemiquinones formed a complex with a high potential FeS protein of succinate dehydrogenase. Ischemia decreased the free radical species in myocardium ≈50%; the initiation of reflow of perfusate resulted in quick increase of the EPR signal. Mitochondria isolated from hearts during control perfusion and after 20–30 min of ischemia were able to produce superoxide radicals in both the NADH-coenzyme Q10 reductase and the bc1 segments of the respiratory chain. The rate of oxyradical generation was significantly higher in mitochondria isolated from ischemic heart. electron paramagnetic resonance; oxygen paradox; oxyradicals; rat heart; semiquinones

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