硫代异鼠李糖甘油二酯(SQDG)的生物合成与功能

The Biosynthesis and Function of Sulfoquinovosyl Diacylglycerol

硫代异鼠李糖甘油二酯 (SQDG)是一种含硫的糖脂 ,分布于高等植物 ,藓类植物 ,蕨类植物 ,藻类植物以及大多数光合细菌的光合膜中。SQDG的含量与生物种类有关。在高等植物中含量一般为总脂的 4% ,而在藻类中其含量变化较大 ,一般为总脂含量的 1 0 %～ 70 %。SQDG的合成是在叶绿体内被膜上完成的 ,催化SQDG合成的酶是UDP_SQ :DAG硫代异鼠李糖基转移酶。SQDG存在于纯化的叶绿体CF0 _CF1 ATPase、LHCⅡ辅基蛋白以及D1 /D2异二聚体蛋白中 ,说明SQDG可能与膜蛋白复合物的结构和功能有关。SQDG还与植物的抗逆性有关。在磷缺乏时 ,SQDG能弥补PG含量的下降 ,使体内阴离子脂的含量维持在一个稳定的水平。近年来还发现SQDG能有效抑制真核生物DNA聚合酶和HIV反转录酶的活性。

Sulfoquinovosyl diacylglycerol(SQDG) is a sulfur_containing glycolipid. It is widely distributed in photosynthetic membranes of all higher plants, mosses, ferns, algae and most photosynthetic bacteria. The content of this lipid in photosynthetic membranes depends on the biological species. In higher plants, the level of this compound amounts to 4% of total lipids. However, the level of SQDG changes greatly in algae, amounting to 10%-70% of total lipids. SQDG is synthesized mainly in the inner envelope membrane. The enzyme catalyzing the reaction is UDP_sulfoquinovose:diacylglycerol sulfoquinovosyltransferase. SQDG seems to play an important role in photosynthetic process. It has been reported that SQDG was associated with several protein complexes in photosynthetic membranes such as the chloroplast CF 0_CF 1 ATPase, the LHCⅡ_apoproteins and native D1/D2 heterodimers. In addition, SQDG is related to the stress response of plants. Under the phosphate limitation conditions, SQDG can partially compensate PG deficiency. In recent years, SQDG has been found to be effective against the activities of eukaryotic DNA polymerase and HIV_reverse transcriptase.