Molecular dynamics of Q(sub A)(super -.) and Q(sub B)(super -.) in photosynthetic bacterial centers studied by pulsed high-field EPR at 95GHz

The anisotropic transverse relaxation times T(sub 2) of the primary and secondary acceptor quinone radical anions Q(sub A)(super -.) and Q(sub B)(super -.) in Zn-substituted photosynthetic bacterial reaction of Rhodobacter sohaeroides R26 by means of 2D high-field-frequency electron spin-echo spectroscopy are investigated. The anisotropy of the relaxation times is related to anisotropic stochastic fluctuations of the quinones in their protein binding pockets, which are temperature-dependant.