J Integr Plant Biol. ›› 1995, Vol. 37 ›› Issue (2): -.

• Research Articles •    

Effect of Cu2+ on PSⅡ Activity and Energy Transfer of Phycobillisome in Intact Cells of Spirulina platensis

Du Lin fang, Fu Hua long and Zou Xiao dong   

Abstract: Addition of Cu2+ at low concentrations, to intact cells of the cyanobacterium, Spirulina platensis, at room temperature, caused an enhancement in intensity of fluorescence emitted by phycocyanin and induced a blue shift at the emission peak, both of which indicated changes in energy transfer within the phycobillisomes. Cu2+ also suppressed the whole-chain electron transport activity (H2O→MV) and water-splitting activity of the photosystem Ⅰ. When isolated phycocyanin and allophycocyanin were exposed to very low concentrations of Cu2+ ions, C-phycocyanin but not allophycocyanin, exhibited decrease not only in the absorbance in the longer wavelength (616--620 nm) region, but also in the fluorescence emission intensity at 647 nm accompanied by a blue shift to 643 nm. These results suggested that Cu2+ selectively bleach C-phycocyanin.

Key words: Cu2+, Spirulina platensis, Photosystem Ⅱ, Phycobiliprotein

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