Electron spin resonance of a sigma-type radical formed by X-irradiation of malonamide

1967 ◽  
pp. 192 ◽  
Author(s):  
N. Cyr ◽  
W. C. Lin
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Resonance ◽  
X Irradiation ◽  
Type Radical

Über die Radikalkonzentration von Rattenleber-Mitochondrien in Abhängigkeit von verschiedenen Faktoren

1968 ◽  
Vol 23 (6) ◽  
pp. 798-803 ◽  
Author(s):  
M. Waldschmidt ◽  
H. Mönig ◽  
J. Schole
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Mitochondrial Protein ◽  
Yeast Cells ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Control Value ◽  
Spin Resonance ◽  
X Irradiation

The concentration of free radicals in freshly prepared ratliver-mitochondria was investigated under different conditions with the aid of electron spin resonance spectroscopy. The electron spin resonance signal at g=2.004 was measured at 77 °K and related to the weight in milligrams of mitochondrial protein. The concentration of free radicals increases with rising body weight or, in other words, with decreasing growth rate of the animals. A plateau is reached with about 1013 radicalcenters per mg protein for grown animals. The concentration of free radicals is 150% of the control value after fasting for 24 hours, whereas it is below the detectable level in cells of ascites hepatoma. We conclude that the concentration of free radicals determined at g = 2.004 is a function of mitochondrial activity. After whole body x-irradiation with a dose of 900 R, a significant decrease of 20% of the signal amplitude was measured. Increasing the dose to 1800 R did not decrease the radical concentration further. These results might be connected with the diminished activity of some flavin enzymes observed in liver mitochondria after x-irradiation in vivo. In further experiments we have incubated the mitochondria in vitro with various inhibitors of flavin enzymes. The individual inhibitors (ammonium-ions, KCN, acetonitrile, glucose) and also malonate reduce the concentration of free radicals to 80% of the control value in the mean if the particles are incubated at 37 °C for 5 minutes. The effect of malonate adds to the effects of the other inhibitors. The inhibitory effect of 2,4-dinitrophenol develops only after a longer incubation time. These results are discussed in connection with the influence of the same inhibitors on the Pasteureffect of yeast cells. Some specific inhibitors of the respiratory chain (Amytal, antimycin A, oligomycin) also diminish the concentration of free radicals.

Electron spin resonance studies of doped synthetic kaolinite. I

Clay Minerals ◽  
1974 ◽  
Vol 10 (4) ◽  
pp. 247-255 ◽  
Author(s):  
B. R. Angel ◽  
J. P. E. Jones ◽  
Peter L. Hall
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hydrothermal Reaction ◽  
Esr Spectrum ◽  
Defect Centre ◽  
Additional Resonance ◽  
Spin Resonance ◽  
X Irradiation ◽  
Lattice Vacancies

AbstractSynthetic kaolinites of varying crystallinity, and in some instances with ideal morphology, have been produced by hydrothermal reaction of aluminiosilicate gels. Synthetic kaolinites doped with Mg2+ and Fe3+ were also obtained.Synthetic kaolinite doped with Fe3+ produced an ESR spectrum at g = 4 identical to spectra observed in natural kaolinites. Following X-irradiation and annealing at ~200°C, synthetic kaolinite doped with Mg2+ exhibited an ESR signal at g = 2·0 identical to a resonance observed in natural kaolinites. It is concluded that the g = 2·0 signal in kaolinite is due to a defect centre stabilized by Mg2+ substitution.All synthetic and natural kaolinites exhibit an additional resonance at g = 2·0 following X-irradiation which can be repeatedly created and destroyed by irradiation and annealing. This resonance is attributed to defects possibly associated either with the substitution of Al3+ for Si4+ in kaolinite or with lattice vacancies.

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