Effect of Eu(3+) on characterization of photosystem II particles from spinach by spectroscopy.

Photosystem II (PSII) particles were purified from Eu(3+)-treated spinach and studied by spectroscopy. The results showed that electron transport rate of PS II was accelerated by Eu3+ treating, that violet shift of the PSII Soret band or Q-band was 6 nm or 2 nm for the ultraviolet-visible (UV-Vis) spectrum, that the violet shift of the PSII fluorescence emission peak was 9 nm for fluorescence emission spectrum, that the PSII Signal II's of low-temperature electron paramagnetic resonance (EPR) spectrum was intensified under light, and that the PSII CD spectrum was similar to that of control. It is suggested that Eu(3+) might bind to the PSII reaction center complex and enhance the electron transport rate of PSII CD; however, Eu(3+) treatment does not change the configuration of the PSII reaction center complex.