The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanth...The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration (15-30 mg·L-1), however, it behaves toxically on them when over used (60 mg·L-1). To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lan-thanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lan-thanum was located in photosystem II (PS II) while there was little lanthanum in photosystem I (PS I). Moreover, size ex-clusion high performance liquid chromatography (SE-HPLC) coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS II proteins for the first time. It was found that lanthanum has two bind-ing sites in PS II: La associates with chlorophyll together with magnesium in PS II by partly replacing magnesium and also shares the common binding sites of PS II proteins to-gether with the inorganic cofactors of calcium and manga-nese, influencing the process of photosynthesis.展开更多
文摘The effects of lanthanum at different concen-trations on the related photosynthetic activities of Hill reac-tion, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration (15-30 mg·L-1), however, it behaves toxically on them when over used (60 mg·L-1). To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lan-thanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lan-thanum was located in photosystem II (PS II) while there was little lanthanum in photosystem I (PS I). Moreover, size ex-clusion high performance liquid chromatography (SE-HPLC) coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS II proteins for the first time. It was found that lanthanum has two bind-ing sites in PS II: La associates with chlorophyll together with magnesium in PS II by partly replacing magnesium and also shares the common binding sites of PS II proteins to-gether with the inorganic cofactors of calcium and manga-nese, influencing the process of photosynthesis.
