REACTIONS OF PHOTORADICALS WITH NITROXIDE SPIN LABELS

The kinetics of reactions of radicals R• with nitroxide spin labels have been studied, the radicals R. being produced by laser photodecomposition of alkylcobalt complexes having the general formula Co(CN)53-R. The rate of reaction of the radicals R• and nitroxide radicals is shown to be a sensitive function of the molecular environment of the nitroxide group, i.e., whether it is bound to a membrane or is free in solution. The ease with which a variety of alkylcobalt compounds Co(CN)53-R. can be prepared with the corresponding radicals R• having different physical and chemical properties, and the ease with which the rate of generation of radicals R• can be varied with laser power, indicates that a number of applications of this to biophysical and biochemical problems may be possible. © 1979, American Chemical Society. All rights reserved.