New applications of electron spin resonance to problems in biochemistry and pharmacology

Adsorbed Molecules on Solvated Layer Silicates: Surface Mobility and Orientation from ESR Studies

“…The r c values were found to be in the range of 10-a~ -11 sec for TEMPO dissolved in the solvents (except glycerol) used in this study ( Table 1). The values of A o for nitroxide probes dissolved in various solvents decrease as the solvent polarity decreases (Chignell, 1974). This relationship was found for the solvents used in the study (Figure 3), demonstrating that Ao increases with increasing dielectric constant.…”

“…Glycerol has a high enough viscosity at room temperature to prevent motional averaging of A and g (Chignell, 1974). The rotational correlation times (zc), which define the time scale of molecular rotation, can be calculated from the peak heights of the ESR spectra by a standard method (Sachs and Latorre, 1974).…”

Effects of growth with ethanol on fermentation and membrane fluidity of Saccharomyces cerevisiae

“…Fluidity of yeast subcellular membrane fractions was determined by means of ESR spectroscopy of the spin label: 5-doxyl-stearic acid (free radical), i.e. (N-oxyl-4,4-dimethyloxolidene derivative of 5-keto stearic acid) (free radical), which had been incorporated into the membranes (Chignell, 1974). This nitroxide derivative of stearic acid is expected to orientate with its alkyl chain adjacent to phospholipid side chains, and with its carboxyl group at the polar/apolar interface near the membrane surface.…”

Spin-labeled carbohydrates

“…In addition to the spin labels covalently bound to polysaccharides, research on films of nitroxyls and polysaccharides was reported.77 Films of acylated chitins, containing one to 12 carbon atoms in the acyl portion, and Tempol (4) were prepared and their ESR spectra recorded at low and high temperatures.77 The correlation time rc at higher temperatures (fast motion) was calculated by using the equation developed by Kivel-son78 while that at lower temperatures (restricted motion) was calculated by using the method of Freed et al 79 The activation energies of the spin probe 4 were determined by means of Arrhenius plots. Plots of log rc vs. the number of carbon atoms in the acyl groups were then constructed.…”

“…A number of books and reviews devoted to different aspects of the technique have appeared since 1968.2-19 Several of these are concerned with the synthesis and chemistry of nitroxyls.8,9'13-16,18 Other articles concentrate on biological applications of ESR and spin labeling. 5,6,[10][11][12][13][14]16,17 The reports Electron Spin Resonance annually cover literature on the spin-labeling technique.…”