Transversal localization of monogalactosyldiacylglycerol and digalactosyldiacylglycerol in spinach thylakoid membranes
Transversal localization of monogalactosyldiacylglycerol and digalactosyldiacylglycerol in spinach thylakoid membranes
复制标题
菠菜类囊体膜中单半乳糖二酰甘油和双半乳糖二酰甘油的横向定位
DOI：
10.1016/0005-2736(85)90299-8
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
P. Siegenthaler
中科院分区：
文献类型：
--
作者：
A. Rawyler;P. Siegenthaler
利用少根根霉脂肪酶研究了菠菜类囊体膜中单半乳糖基甘油二酯（MGDG）和双半乳糖基甘油二酯（DGDG）的跨膜分布。水解动力学，表示为半对数图，进行了恒定的散装pH值下的盐浓度和温度范围很广。无论使用何种条件，DGDG总是显示两个恒定振幅的池。MGDG的行为更为复杂。根据环境条件，可以证明有两个或三个池。我们已经开发了一个简单的原理，它允许区分动力学池（确定为在外单层内以不同水解速率降解的脂质分子的不同群体）和拓扑池（对应于经典的外部/内部分布）。这表明，表面电位和温度参与控制的类囊体膜脂的包装压力，探测的脂解酶。我们定义了一组有限的条件下，它是可能的，以获得可靠的估计半乳糖脂类囊体膜的横向分布。对于菠菜，DGDG和MGDG的外部/内部比分别为15 85和65 35。考虑到这些脂质对总酰基脂质组成的贡献（mol%），可以推断总半乳糖脂均匀分布在类囊体膜的两个单层内。这些结果的整体类囊体膜的分子组织的影响进行了讨论。
The lipase from Rhizopus arrhizus has been used to determine the transmembrane distribution of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) in spinach thylakoid membranes. The hydrolysis kinetics, expressed as semilog plots, were carried out at constant bulk pH under a wide range of salt concentration and temperatures. DGDG always showed two pools of constant amplitude, regardless of the conditions used. The behavior of MGDG was more complex. Depending on environmental conditions, two or three pools could be evidenced. We have developed a simple rationale which allows to distinguish between kinetic pools (identified as different populations of lipid molecules being degraded at different hydrolysis rates within the outer monolayer) and topological pools (corresponding to the classical outside/inside distribution). It is suggested that the surface potential and temperature are involved in the control of the packing pressure of thylakoid membrane lipids, as probed by the lipolytic enzyme. We defined a limited set of conditions under which it is possible to obtain reliable estimations of the transversal distribution of galactolipids in thylakoid membranes. For spinach, the outside/inside ratios are 15 85 for DGDG and 65 35 for MGDG. Taking into account the contribution (in mol%) of these lipids to the total acyl lipid composition, it is deduced that total galactolipids are equally distributed within the two monolayers of the thylakoid membrane. The implications of these results for the overall molecular organization of the thylakoid membrane will be discussed.