Institute for Bioscience and Biotechnology Research, Rockville, Maryland.
Biology Division, University of Missouri, Columbia, Missouri; NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland; Department of Physiology and Biophysics, University of California at Irvine, Irvine, California.
Biophys J. 2023 Mar 21;122(6):1086-1093. doi: 10.1016/j.bpj.2023.01.031. Epub 2023 Jan 26.
The cationic lipid 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) is one of the original synthetic cationic lipids used for the liposomal transfection of oligonucleotides in gene therapy. The key structural element of DOTAP is its quaternary ammonium headgroup that is responsible for interactions with both nucleic acids and target cell membranes. Because these interactions are fundamental to the design of a major class of transfection lipids, it is important to understand the structure of DOTAP and how it interacts with halide counterions. Here, we use x-ray and neutron diffraction techniques to examine the structure of DOTAP and how chloride (Cl-) and iodide (I-) counterions alter the hydration properties of the DOTAP headgroup. A problem of particular interest is the poor solubility of DOTAP/I- in water solutions. Our results show that the poor solubility results from very tight binding of the I- counterion to the headgroup and the consequent expulsion of water. The structural principles we report here are important for assessing the suitability of DOTAP and its quaternary ammonium derivatives for transfection.
阳离子脂质 1,2-二油酰基-3-三甲铵丙烷（DOTAP）是最初用于基因治疗中寡核苷酸脂质体转染的合成阳离子脂质之一。DOTAP 的关键结构元素是其季铵头基，负责与核酸和靶细胞膜相互作用。由于这些相互作用是一类主要转染脂质设计的基础，因此了解 DOTAP 的结构以及它如何与卤化物抗衡离子相互作用非常重要。在这里，我们使用 X 射线和中子衍射技术来研究 DOTAP 的结构以及氯离子（Cl-）和碘离子（I-）抗衡离子如何改变 DOTAP 头基的水合特性。一个特别感兴趣的问题是 DOTAP/I-在水溶液中的溶解度很差。我们的结果表明，较差的溶解度是由于 I-抗衡离子与头基的紧密结合以及随之而来的水分子的驱逐。我们在这里报告的结构原则对于评估 DOTAP 及其季铵衍生物用于转染的适用性非常重要。
