Rudolphi-Skórska Elżbieta, Filek Maria, Zembala Maria
Department of Biochemistry, Biophysics and Biotechnology, Institute of Biology, Pedagogical University of Cracow, Podchorążych 2, Cracow, 30-084, Poland,
J Membr Biol. 2014 Jul;247(7):639-49. doi: 10.1007/s00232-014-9681-9. Epub 2014 May 27.
The impact of reaction of galactolipids with ozone on the physicochemical properties of their monolayers was examined. In Megli and Russo (Biochim Biophys Acta, 1778:143-152, 2008), Cwiklik and Jungwirth (Chem Phys Lett, 486:99-103, 2010), Jurkiewicz et al. (Biochim Biophys Acta, 1818:2388-2402, 2012), Khabiri et al. (Chem Phys Lett, 519:93-99, 2012), and Conte et al. (Biochim Biophys Acta, 1828:510-517, 2013), the properties of layers formed from model mixtures composed of chosen lipids and selected oxidation products were studied, whereas in this work, question was raised as to how the oxidation reactions taking place in situ affect the physical properties of the galactolipid layers. So, set experiment should take into account the effect of all reaction products. The mechanical characteristics of monolayers of monogalactosyldiacyl-glycerol (MGDG) and digalactosyldiacylglycerol (DGDG) were determined by Langmuir trough technique, and the electrical properties of liposomes formed from these lipids by measuring their electrophoretic mobility. Considerable loss of galactolipid molecules forming monolayers was found at ozone concentrations (in aqueous medium) higher than 0.1 ppm with a stronger effect measured for MGDG. That goes along with the greater amounts of MDA found in the extracts of oxidized MGDG films compared with DGDG. Based on this, it was concluded that an additional galactose group present in DGDG molecules acts protectively under oxidative conditions. The surface tension of the solutions (of small volume) contacting the oxidized galactolipids films was significantly reduced, indicating the presence of soluble in polar media, surface active reaction products. The presence of α-tocopherol in mixtures with tested galactolipids at a molar ratio of lipid to tocopherol equal to 1.7:1 caused some inhibition of lipid oxidation, reducing the decrease of amount of lipid particles forming the monolayer. Here, also protective effect of α-tocopherol was greater for the MGDG compared to DGDG.
研究了半乳糖脂与臭氧反应对其单分子层物理化学性质的影响。在梅格利和鲁索（《生物化学与生物物理学报》，1778:143 - 152，2008年）、茨维克利克和容维尔特（《化学物理快报》，486:99 - 103，2010年）、尤尔凯维茨等人（《生物化学与生物物理学报》，1818:2388 - 2402，2012年）、哈比里等人（《化学物理快报》，519:93 - 99，2012年）以及孔特等人（《生物化学与生物物理学报》，1828:510 - 517，2013年）的研究中，对由选定脂质和选定氧化产物组成的模型混合物形成的层的性质进行了研究，而在本研究中，提出了原位发生的氧化反应如何影响半乳糖脂层物理性质的问题。因此，设定的实验应考虑所有反应产物的影响。通过朗缪尔槽技术测定了单半乳糖基二酰基甘油（MGDG）和二半乳糖基二酰基甘油（DGDG）单分子层的力学特性，并通过测量由这些脂质形成的脂质体的电泳迁移率来测定其电学性质。发现在臭氧浓度（在水介质中）高于0.1 ppm时，形成单分子层的半乳糖脂分子有相当大的损失，对MGDG的影响更强。这与氧化MGDG膜提取物中发现的丙二醛（MDA）量比DGDG中的更多是一致的。基于此，得出结论：DGDG分子中存在的额外半乳糖基团在氧化条件下起保护作用。与氧化的半乳糖脂膜接触的（小体积）溶液的表面张力显著降低，表明存在可溶于极性介质的表面活性反应产物。在与测试的半乳糖脂的混合物中，当脂质与生育酚的摩尔比等于1.7:1时，生育酚的存在对脂质氧化有一定抑制作用，减少了形成单分子层的脂质颗粒数量的减少。同样，生育酚对MGDG的保护作用比对DGDG的更大。
