A D-band (130 GHz) EPR study of the primary electron donor triplet state in photosynthetic reaction centers of Rhodobacter sphaeroides R26

Author(s):
Paschenko, S.V.; Gast, P.; Hoff, A.J.
Published
2001
Publication type
Article / Letter to editor

Abstract

A high-field (D-band, 130 GHz) electron spin echo-detected spectrum of the primary electron donor triplet state, P-3, in quinone-depleted photosynthetic reaction centers from the bacterium Rhodobacter sphaeroides R26 is obtained. It shows a significant g-anisotropy, which is larger than that of the primary donor oxidized state, P+. Simulation gives the triplet g-tensor principal values of 2.0037, 2.0028, and 2.0022 (precision +/-0.0001), assuming that the g-tensor is coaxial to a zerofield splitting tensor. The P-3 spectral lineshape reveals an orientational anisotropy of the triplet quantum yield. We explain this anisotropy as arising from the difference in the main values and relative orientations between the g-tensors of P+ and I-A(-.) in the primary radical pair (the triplet state's precursor).

Date issued
2001-01-01
Language
English
Publisher
SPRINGER WIEN
Is part of
Applied Magnetic Resonance (2001), Vol. 21, no. 3-4, p. 325-334
hdl
1887/3590007
doi
10.1007/BF03162411