ESE relaxation measurements in photosystem II. The influence of the reaction center non-heme iron on the spin-lattice relaxation of Tyr D.
The spin-lattice relaxation of the tyrosine radical D. in Photosystem II particles was studied at 4.2 K in samples in which flash-induced oscillations of the oxidation state of the Mn-cluster of the oxygen evolving system were abolished by addition of ANT2P, leaving Fe2+/Fe3+ oscillations intact. Samples subjected to 0, 1 or 2 light-flashes all showed the same relaxation kinetics. No period-2 oscillation in the spin-lattice relaxation corresponding to the Fe2+/Fe(3+)-oscillation was observed. Thus the T1-oscillations of D. as a function of flash number in untreated samples are solely caused by the charge-oscillations of the Mn-cluster (1989, Biochim, Biophys. Acta 973, 428-442).
Bosch
M K
MK
Department of Biophysics, Huygens Laboratory, Leiden University, The Netherlands.
Evelo
R G
RG
Styring
S
S
Rutherford
A W
AW
Hoff
A J
AJ
D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D014443:Tyrosine / Q000737:chemistry*
D005609:Free Radicals; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D014443:Tyrosine; D007501:Iron; D010100:Oxygen