海洋管藻目绿藻刺松藻光系统Ⅰ复合物的分离

Isolation of PSⅠ from a Siphonous Marine Green Alga, Codium fragile

采用TritonX 10 0蔗糖密度梯度离心法 ,从管藻目绿藻刺松藻中分离到三种不同形式的光系统Ⅰ (PSⅠ )复合物 .区带Ⅲ富含PSⅠ核心复合物 (CCⅠ ) ,叶绿素 (Chl)a/b >2 0 ,在温和的聚丙烯酰胺凝胶电泳 (PAGE)中只显示一条PSⅠ中心复合物CPⅠ条带 .区带Ⅳ和Ⅴ在 436和 6 74nm、 46 7和 6 5 0nm以及 5 40nm的吸收表明 ,含有Chla、b及管藻黄素和管藻素 ,Chla/b比值分别为 3 2 3和 2 4.经PAGE检测 ,有CPⅠ和CPⅠa两种PSⅠ色素蛋白复合物带 ,因此区带Ⅳ和Ⅴ是由CCⅠ和含量不等的捕光复合物LHCⅠ构成的PSⅠ颗粒 .区带Ⅲ只有 6 6和 5 6ku两种核心多肽 ;区带Ⅳ和Ⅴ除了 6 6、 5 6ku多肽以外 ,还有 4种分子质量为 2 5 ,2 6 ,2 6 2和2 7 5ku的LHCⅠ多肽 .室温荧光光谱显示 ,分离物中的各种光合色素之间保持着良好的能量传递关系 ,由Chlb及管藻黄素和管藻素吸收的能量都可以传递给Chla.

Three different forms of PSⅠ complexes were isolated from a siphonous marine green alga, Codium fragile , by Triton X 100 sucrose gradient centrifugation. Zone Ⅲ had a Chl a/b>20, and designated as PSⅠ core complex CCⅠ because it created only CPⅠ band in mild PAGE. Zone Ⅳ and Ⅴ had absorption at 436 and 674 nm, 467 and 650 nm, and 540 nm, suggesting the presence of Chl a, Chl b, siphonaxanthin and siphonein, Chl a/b were 3 23 and 2 4, respectively. Both CPⅠ and CPⅠa bands were observed when they were subjected to mild PAGE. Therefore, Zone Ⅳ and Ⅴ were different forms of PSⅠ complexes that consisted of CCⅠ and different amount of light harvesting complex LHCⅠ. Zone Ⅲ contained only 66 and 56 ku peptides in SDS PAGE, while Zone Ⅳ and Ⅴ had 4 different LHCⅠ peptides of 25,26,26 2 and 27 5 ku in addition to 66, 56 ku peptides. Fluorescence emission spectra showed that efficient energy transfer were kept among pigments in isolated PSⅠ complexes. Excitation energy absorbed by Chl b, siphonaxanthin and siphonein can be transferred to Chl a.