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Rapid-scan EPR of immobilized nitroxides.


Yu ZZhelin , Quine RW Richard W , Rinard GA George A , Tseitlin M Mark , Elajaili H Hanan , Kathirvelu V Velavan , Clouston LJ Laura J , Boratyński PJ Przemysław J , Rajca A Andrzej , Stein R Richard , Mchaourab H Hassane , Eaton SS Sandra S , Eaton GR Gareth R . Journal of magnetic resonance (San Diego, Calif. : 1997). 2014 10 ; 247(). 67-71


X-band electron paramagnetic resonance spectra of immobilized nitroxides were obtained by rapid scan at 293 K. Scan widths were 155 G with 13.4 kHz scan frequency for (14)N-perdeuterated tempone and for T4 lysozyme doubly spin labeled with an iodoacetamide spirocyclohexyl nitroxide and 100 G with 20.9 kHz scan frequency for (15)N-perdeuterated tempone. These wide scans were made possible by modifications to our rapid-scan driver, scan coils made of Litz wire, and the placement of highly conducting aluminum plates on the poles of a Bruker 10″ magnet to reduce resistive losses in the magnet pole faces. For the same data acquisition time, the signal-to-noise for the rapid-scan absorption spectra was about an order of magnitude higher than for continuous wave first-derivative spectra recorded with modulation amplitudes that do not broaden the lineshapes.