Bondar O P, Rowe E S
Veterans Affairs Medical Center, Kansas City, Missouri 64128, USA.
Biophys J. 1996 Sep;71(3):1440-9. doi: 10.1016/S0006-3495(96)79345-1.
Phosphatidylethanol is formed when ethanol substitutes in the transphosphatidylation reaction catalyzed by phospholipase D. The structural and thermotropic properties of dipalmitoylphosphatidylethanol and dimyristoylphosphatidylethanol have been studied using differential scanning calorimetry, fluorescence spectroscopy, and 31P nuclear magnetic resonance. These lipids exist in a bilayer phase with no indication of nonbilayer phase formation, as shown by 31P nuclear magnetic resonance. It was found that the phase behavior of these phospholipids before and during the main chain melting transition is different in 50 mM Tris buffer compared to salt solutions. The phase transition behavior and the 6-propionyl-2-(dimethylamino)naphthalene (Prodan) fluorescence spectra for both lipids are consistent with the formation of the interdigitated gel phase under certain conditions. Both lipids become interdigitated in Tris-HCl, and ethanol enhances the formation of this phase. Comparative studies of the 6-propionyl-2-(dimethylamino)naphthalene spectra in dipalmitoylphosphatidylglycerol, dielaidoylphosphatidylethanolamine, and dipalmitoylphosphatidylcholine further elucidate the value and limitations of this probe as a diagnostic tool for lipid structure.
磷脂酰乙醇是在磷脂酶D催化的转磷脂酰基反应中乙醇发生取代时形成的。利用差示扫描量热法、荧光光谱法和31P核磁共振法研究了二棕榈酰磷脂酰乙醇和二肉豆蔻酰磷脂酰乙醇的结构和热致性质。如31P核磁共振所示，这些脂质以双层相存在，没有形成非双层相的迹象。研究发现，与盐溶液相比，在50 mM Tris缓冲液中，这些磷脂在主链熔化转变之前和期间的相行为有所不同。两种脂质的相变行为和6-丙酰基-2-（二甲基氨基）萘（Prodan）荧光光谱与在某些条件下形成交叉指状凝胶相是一致的。两种脂质在Tris-HCl中都会形成交叉指状结构，乙醇会促进该相的形成。对二棕榈酰磷脂酰甘油、二反油酰磷脂酰乙醇胺和二棕榈酰磷脂酰胆碱中6-丙酰基-2-（二甲基氨基）萘光谱的比较研究进一步阐明了该探针作为脂质结构诊断工具的价值和局限性。
