Caracciolo Giulio, Pozzi Daniela, Amenitsch Heinz, Caminiti Ruggero
Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185 Roma, Italy.
Langmuir. 2006 Apr 25;22(9):4267-73. doi: 10.1021/la0534423.
Using simultaneous synchrotron small- and wide-angle X-ray diffraction (SWAXD), we investigated the thermotropic behavior of a cationic lipid mixture of DOTAP-DOPC (1,2-dioleoyl-3-trimethylammonium-propane-dioleoylphosphatidylcholine) liposomes complexed with calf thymus DNA. The DOTAP-DOPC/DNA complex reacts to temperature change by a bilayer compression normal to its surface and an expansion of the DNA in the plane of the rod lattice. By applying two independent recently developed models, we show here for the first time that the thermotropic dilatation area of lipid headgroups within the complexes is not isotropic but occurs parallel to the 1D DNA lattice (i.e., along the direction perpendicular to the DNA axis). Our results shed light on the role of spatial dimensionality in the DNA packing density within lamellar lipoplexes and provide experimental evidence that the interaction between DNA molecules confined between lipid bilayers can be regarded as a 1D problem.
利用同步加速器小角和广角X射线衍射（SWAXD）技术，我们研究了与小牛胸腺DNA复合的DOTAP-DOPC（1,2-二油酰基-3-三甲基铵丙烷-二油酰基磷脂酰胆碱）脂质体阳离子脂质混合物的热致行为。DOTAP-DOPC/DNA复合物通过垂直于其表面的双层压缩和棒状晶格平面内DNA的膨胀来响应温度变化。通过应用两个最近独立开发的模型，我们首次表明，复合物中脂质头部基团的热致膨胀区域不是各向同性的，而是平行于一维DNA晶格发生（即沿着垂直于DNA轴的方向）。我们的结果揭示了空间维度在层状脂质复合物中DNA堆积密度中的作用，并提供了实验证据，即限制在脂质双层之间的DNA分子之间的相互作用可被视为一维问题。
