. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SULFIDE-GENERATED FREE RADICALS 53 dation have been proposed (4. 7). no direct experimental support tor such a mechanism has been provided to date. We have therefore employed electron paramagnetic reso- nance (EPR) spin trapping to gather direct evidence that free-radical intermediates are produced during sultide oxi- dation. EPR spectrometry is similar to nuclear magnetic resonance (NMR) spectrometry, but relies on magnetic mo- ments resulting from unpaired electrons instead of those from the atomic nucleus. Samples are exp
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SULFIDE-GENERATED FREE RADICALS 53 dation have been proposed (4. 7). no direct experimental support tor such a mechanism has been provided to date. We have therefore employed electron paramagnetic reso- nance (EPR) spin trapping to gather direct evidence that free-radical intermediates are produced during sultide oxi- dation. EPR spectrometry is similar to nuclear magnetic resonance (NMR) spectrometry, but relies on magnetic mo- ments resulting from unpaired electrons instead of those from the atomic nucleus. Samples are exposed to micro- wave radiation at a fixed wavelength and amplitude while a magnetic field is swept through an appropriate range of field densities. At appropriate combinations of wavelength and magnetic field strength, the unpaired electrons will resonate, thereby absorbing microwave energy. This absorbance is recorded as the first derivative. In an EPR spectrum, the relative positions of peaks (lines) are more important than their absolute positions, so spectra typically are plotted with no abscissa, only a scale bar indicating the change in mag- netic field strength over a given distance. The ordinate is in arbitrary absorbance units. Spin trapping is a technique for detecting ephemeral radicals by providing a molecule that preferentially reacts with them, forming more stable radical adducts with characteristic spectra. These spectra typically result from a primary peak, due to the radical that was trapped, being split one or more times by adjacent paramag- netic nuclei, typically hydrogen and nitrogen. The splitting of peaks is the result of the magnetic moments of the udduct being oriented either parallel or antiparallel to the magnetic moments of adjacent nuclei, with either orientation being equally likely. The magnetic field of half of the population of adducts will be incrementally increased, while that of the other half will be equally decreased. The values of these spl
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
