The cation radical of the primary donor P700 of photosystem I (PS I) is investigated by ESEEM on single crystals of PS I from the cyanobacterium Synechococcus elongatus. The nuclear quadrupole parameters Κ and η of five different 14N nuclei are determined and 14N hyperfine couplings (hfc's) of P.+700 are evaluated. For comparison the cation of methyl-chlorophyllide a is studied in frozen solution. The 14N hfc data agree with published results for the 15N-labeled cation radicals of P700 and chlorophyll a and are discussed in terms of a chlorophyll a dimer model for the cation radical P.+700.
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry