A method using nitroxide radical spin labels for determining both the isotropic rotational correlation time and the "rigid limit" value of the nitrogen hyperfine coupling along the pzorbital (Az) is described. The method requires measurement of the same sample under unchanged conditions at both X(9.5 GHz)- and Q(35 GHz)-bands, and is valid for rotational correlation times between 10-6and 10-8sec. In this context the "rigid limit" value of Azis in the absence of rotational diffusion but with fast restricted librational motions unchanged, and its measurement becomes a useful spectroscopic observable. Extension of the method to anisotropic motion, particularly as may occur in phospholipid bilayers, is discussed. © 1980.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below