Kõiv A, Kinnunen P K
Department of Medical Chemistry, University of Helsinki, Finland.
Chem Phys Lipids. 1994 Jun 24;72(1):77-86. doi: 10.1016/0009-3084(94)90018-3.
Binding of DNA to dimyristoylphosphatidylcholine (DMPC) liposomes containing different sphingosine derivatives was investigated. DNA labelled with adriamycin was used as a fluorescence quencher and its membrane association was observed by resonance energy transfer from liposomes incorporating a pyrene-derivatized lipid bisPDPC as a donor and containing 19 mol% of sphingosine, dihydro-, phyto- or dimethylsphingosine. As revealed by differential scanning calorimetry, the thermal phase behaviour of multilamellar liposomes containing these sphingolipids was also significantly altered by DNA. Attachment of DNA to liposomes containing sphingosylphosphorylcholine was much weaker, and no binding of DNA to membranes containing N-acetylsphingosine, N-stearoylsphingosine or sphingomyelin was observed. The membrane binding of DNA was dependent on pH and could be reversed by the inclusion of phosphatidic acid (eggPA) into the liposomes. Analogously, the association of cytochrome c with eggPA could be reversed by the DNA-binding sphingosines. These findings lend support to our previous proposal that the DNA-sphingosine interaction is electrostatic and requires the presence of a positive charge in the latter. Accordingly, sphingosines carrying a protonated amino group attach DNA to membranes, while blocking of the amino group by N-acylation abolishes this interaction.
研究了DNA与含有不同鞘氨醇衍生物的二肉豆蔻酰磷脂酰胆碱（DMPC）脂质体的结合情况。用阿霉素标记的DNA作为荧光猝灭剂，通过共振能量转移观察其与膜的结合，该共振能量转移来自掺入芘衍生脂质双（1 - 棕榈酰 - 2 - 二棕榈酰磷脂酰胆碱）（bisPDPC）作为供体且含有19摩尔%鞘氨醇、二氢鞘氨醇、植物鞘氨醇或二甲基鞘氨醇的脂质体。差示扫描量热法显示，含有这些鞘脂的多层脂质体的热相行为也因DNA而显著改变。DNA与含有鞘氨醇磷酸胆碱的脂质体的结合较弱，且未观察到DNA与含有N - 乙酰鞘氨醇、N - 硬脂酰鞘氨醇或鞘磷脂的膜的结合。DNA与膜的结合取决于pH值，并且通过在脂质体中加入磷脂酸（鸡蛋磷脂酸，eggPA）可以使其逆转。类似地，细胞色素c与鸡蛋磷脂酸的结合也可以被与DNA结合的鞘氨醇逆转。这些发现支持了我们之前的提议，即DNA - 鞘氨醇相互作用是静电作用，并且后者需要存在正电荷。因此，携带质子化氨基的鞘氨醇将DNA附着到膜上，而通过N - 酰化阻断氨基则消除了这种相互作用。
