Effects of CeCl3 on Energy Transfer and Oxygen Evolution in Spinach Photosystem II

Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce3+ on energy transfer and oxygen evolution in photosystem II (PS II) isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce3+ treatment at low concentration could suitably change PS II microenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PS II protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PS II (fluorescence quantum yield) and its oxygen evolving rate were enhanced by Ce3+.