High-field (94-GHz) EPR spectroscopy on the S(2) multiline signal of Photosystem II.
The multiline signal of the S(2) state in Photosystem II was measured both in frozen-solution and single-crystal preparations from the cyanobacterium Thermosynechococcus elongatus. The frozen-solution EPR spectrum shows a gaussian-like line shape without any resolution of Mn hyperfine couplings. This line shape can be understood on the basis of the single-crystal spectra, where a strong orientation dependence of partially resolved hyperfine structures appears. Simulation of the frozen-solution spectrum on the basis of Mn hyperfine couplings taken from published pulse-ENDOR data yields a fully rhombic g-matrix for the multiline signal with principal components 1.997, 1.970, and 1.965. The resulting isotropic g-value g(iso)=1.977 is surprisingly small compared to other manganese complexes containing manganese ions in the formal oxidation states three and four.
Teutloff
Christian
C
Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany.
Kessen
Sven
S
Kern
Jan
J
Zouni
Athina
A
Bittl
Robert
R
D003460:Crystallization; D000458:Cyanobacteria / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D012996:Solutions
D045332:Photosystem II Protein Complex; D012996:Solutions