Positional distribution of fatty acids on the glycerol backbone during the biosyn-thesis of glycerolipids in Ectocarpus fasciculatus  

作　　者：XU Yinong WANG Zeneng VAN Xiaojun LIN Wei LI Liangbi KUANG Tingyun 

机构地区：[1]Key Laboratory of Photosynthesis and Environmental Molecular Physiology,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China [2]Key Laboratory of Experimental Marine Biology,Institute of Marine Biology,Chinese Academy of Sciences,Qingdao 266071,China

出　　处：《Chinese Science Bulletin》2002年第21期1802-1806,共5页

基　　金：This work was supportedby the National Natural Science Foundation of China (Grant No. 39890390), the One-Hundred-Scientist Program of the Chinese Academy of Sciences, the State Basic Research Development Plan of China (Grant No. G1998010100) and the I

摘　　要：The biosynthesis of glycolipids in E.fascicula-tus was studied by 14C label and chase. The fatty acids in sulphoquinovosyl diacylglycerol (SQDG) were almost 16-car-bon and 18-carbon ones. In addition to the two fatty acids, monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) contained 8.5 mol% and 31.0 mol% of eicosapentaenoic acid (20 : 5), respectively, and this fatty acid was usually distributed in the sn-1 position of the glyc-erol backbone. When plants were incubated with [2-14C] acetate, differences existed in the positional distribution of the labeled fatty acids in sn-1 and sn-2 among the three glycerolipids. In SQDG, 14C-labeled fatty acids were distributed uniformly in the sn-1 and sn-2 positions. In DGDG, 14C-labeled fatty acids were mainly distributed in the sn-2 position. In MGDG, the radioactivity of fatty acids in sn-1 position was far greater than that in sn-2 position after a 30 min pulse label, and the difference in radioactivity between the two positionsThe biosynthesis of glycolipids in E. fasciculatus was studied by 14C label and chase. The fatty acids in sulphoquinovosyl diacylglycerol (SQDG) were almost 16-carbon and 18-carbon ones. In addition to the two fatty acids, monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) contained 8.5 mol% and 31.0 mol% of eicosapentaenoic acid (20: 5), respectively, and this fatty acid was usually distributed in the sn-1 position of the glycerol backbone. When plants were incubated with [2?14C] acetate, differences existed in the positional distribution of the labeled fatty acids in sn-1 and sn-2 among the three glycerolipids. In SQDG., 14C-labeled fatty acids were distributed uniformly in the sn-1 and sn-2 positions. In DGDG., 14C-labeled fatty acids were mainly distributed in the sn-2 position. In MGDG., the radioactivity of fatty acids in sn-1 position was far greater than that in sn-2 position after a 30 min pulse label, and the difference in radioactivity between the two positions decreased rapidly. The above results indicated that differences in the positional distribution of 14C-labeled fatty acids between sn-1 and sn-2 positions might be related to 20: 5 and the biosynthesis of DGDG. Our results also suggested that E. fasciculatus had the same DGDG biosynthetic pathway as that in higher plants and galactosyl transferase was selective for MGDG.

关 键 词：E. fasciculatus GLYCEROLIPID fatty acid isotope label. 

分 类 号：O623[理学—有机化学]