Premium
Determination of the distance between Y ox⋅ Z and Q −⋅ A in photosystem II by pulsed EPR spectroscopy on light‐induced radical pairs
Author(s) -
Zech Stephan G.,
Kurreck Jens,
Renger Gernot,
Lubitz Wolfgang,
Bittl Robert
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01628-7
Subject(s) - chemistry , p700 , photosystem ii , electron paramagnetic resonance , spectroscopy , photosystem i , microsecond , plastoquinone , analytical chemistry (journal) , crystallography , photochemistry , nuclear magnetic resonance , photosynthesis , physics , biochemistry , thylakoid , chloroplast , quantum mechanics , astronomy , chromatography , gene
Out‐of‐phase electron spin echo envelope modulation (ESEEM) spectroscopy was used to determine the distances within two consecutive radical pair states initiated by a laser flash in photosystem II membrane fragments at pH 11. The distance between the spin density centers of the primary electron donor cation radical, P +⋅ 680 , and the reduced plastoquinone acceptor, Q −⋅ A , has been found to be 27.7±0.7 Å in agreement with previous results. Near room temperature and at high pH, P +⋅ 680 is reduced by Y Z , a redox active tyrosine residue, on a sub‐microsecond timescale. As a consequence, the subsequent radical pair state, Y ox⋅ Z Q −⋅ A , could be investigated after almost complete reduction of P +⋅ 680 by Y Z . The determined dipolar electronic spin‐spin coupling within the radical pair Y ox⋅ Z Q −⋅ A corresponds to a distance of 34±1 Å between the two molecules.