EFFECTS OF COPPER ON THE CHLOROPHYLLPROTEIN COMPLEXES COMPONENTS AND SOME SPECTRAL PROPERTIES OF CHLOROPLAST THYLAKOID MEMBRANES

The chlorophyll-protein complexes of spinach and Chinese cabbage chloroplast thylakoid membranes could be resolved by SDS-PAGE into 8 and 7 chlorophyll-containing bands respectively. After treatment of Cu²⁺-Chelators such as bathocuproine and histidine, the experimental results indicated that the CPIa, CPI and LHCP₂ bands of both plants were damaged, and the amount of LHCP₃ band of them obviously increased. After treatment of Cu²⁺, the experimental results indicated that Cu²⁺ led to the loss of CPa₁ band of spinach and CPa band of Chinese cabbage. Cu²⁺ could change the spectral properties of the CPI band of spinach that led to a shift of the red maxima absorption from 678 nm to 672 nm, and appeared a very weak shoulder at 652 nm, and also showed a fluorescence emission peak at 679 nm, so that it became similar to the property of LHC-Ⅱ. Cu²⁺ could change the spectral properties of LHCP₁ and LHCP₂ bands of both plants that led to a shift of the red maxima absorption from 672 nm to 668 nm or 69 nm, and led to the LHCP₂ band show a main fluorescence emission peak at 724 nm, so that it is likely to close to the property of LHC-Ⅰ. Therefore, it is suggested that a possible role of Cu²⁺ is in regulating the energy distributionbetween reaction center and light-harvesting chlorophyll protein complexes and the light-harvesting chlorophyll protein complexes themselves by allosteric effect in both photosystems.