Electron paramagnetic resonance transfer

Thomas, D.D., Dalton, L.R., and Hyde, J.S. 1976. Rotational diffusion studied by passage saturation transfer electron paramagnetic resonance. The Journal of Chemical Physics 65 3006-3024. 

The possibility that there might be long-range electron transfer between redox-active centers in enzymes was first suspected by biochemists working on the mechanism of action of metalloenzymes such as xanthine oxidase which contain more than one metal-based redox center. In these enzymes electron transfer frequently proceeds rapidly but early spectroscopic measurements, notably those by electron paramagnetic resonance, failed to provide any indication that these centers were close to one another. 

A number of papers have reported studies on pyrimidine radical cations. 1-Methylthymine radical cations generated via a triplet-sensitized electron transfer to anthraquinone-2,6-disulfonic acid were detected by Fourier transform electron paramagnetic resonance (FTEPR). The parent 1-methylthymine radical cation, and its transformation to the N(3)-deprotonated radical cation, were observed. Radical cations formed by addition of HO and POs" at C(6) were also detected depending on the pH. Similarly, pyrimidine radical cations deprotonated at N(l) and C(5)-OH were detected from the reaction of 804 with various methylated pyrimidines." These radicals are derived from the initial SO4 adducts of the pyrimidines. Radical cations of methylated uracils and thymines, generated by electron transfer to parent ions of... 

Edge-to-edge distance, photoinduced electron transfer rate constants, I60,l62f Electron paramagnetic resonance apparatus block... 

Shorthand notations such as ET (electron transfer), HAT (hydrogen atom transfer), BDE (bond dissociation energy), NHE (normal hydrogen electrode), CV (cyclic voltammetry), LFP (laser flash photolysis), EPR (electron paramagnetic resonance) and KIE (kinetic isotope effect) will be used throughout the chapter. In addition, recurring chemical compounds such as TEMPO (2,2,6,6-tetramethylpiperidine-Ai-oxyl), HBT (1-hydroxyben-zotriazole), BTNO (benzotriazole-A-oxyl), HPI (iV-hydroxyphthalimide), PINO (phthal-imide-iV-oxyl), NHA (A-hydroxyacetanilide) and a few others will be referred to by means of the capital-letter acronym. 

Alanine dosimeters are based on the ability of 1-a alanine (a crystalline amino acid) to form a very stable free radical when subjected to ionizing radiation. The alanine free radical yields an electron paramagnetic resonance (EPR) signal that is dose dependent, yet independent of the dose rate, energy type, and relatively insensitive to temperature and humidity. Alanine dosimeters are available in the form of pellets or films and can be used for doses ranging from 10 Gy to 200 kGy. A reference calibration service using the alanine EPR system was developed and the scans were sent to the service center by mail. Currently the available system allows transferring the EPR scan to a NIST server for a calibration certificate. This way the procedure has been shortened from days to hours. ... 

Time-resolved electron paramagnetic resonance served to detected the short-lived triplet state of the keto tautomer (238) of 2-(2-hydroxyphenyl)benzothiazole (239) generated by excited state intramolecular proton transfer (92CC641). 

Jin F, Leitich J, von Sonntag C (1993) The superoxide radical reacts with tyrosine-derived phenoxyl radicals by addition rather than by electron transfer. J Chem Soc Perkin Trans 2 1583-1588 Jones CM, Lawrence A, Wardman P, Burkitt MJ (2002) Electron paramagnetic resonance with spin trapping investigation into the kinetics of glutathione oxidation by the superoxide radical re-evaluation of the rate constant. Free Rad Biol Med 32 982-900 Jones CM, Lawrence A, Wardman P, Burkitt MJ (2003) Kinetics of superoxide scavenging by glutathione an evaluation of its role in the removal of mitochondrial superoxide. Biochem Soc Trans 31 1337-1339... 

---