Effect of Lipidic Cubic Phase Structure on Functionality of the Dopamine 2L Receptor: Implications for in Meso Crystallization

The success of the lipidic cubic phase for crystallization, particularly of integral membrane proteins, is increasing. In the past two years, more than 25% of membrane protein structures have been solved within the biomimetic environment of the lipidic cubic phase. However, the relationship between the lipid matrix and crystal growth still remains a mystery. Herein we show that the bilayer structure of the lipidic cubic phase is crucial to retention of the functionality of the dopamine D2 long receptor. Destruction of the cubic architecture at higher protein concentrations is associated with a significant drop in the amount of functional receptor. This has profound implications for in meso crystallization and suggests that preliminary experiments to determine the maximum protein loading within the lipidic cubic phase must be carried out prior to in meso crystallization experiments

Self-Assembled Functional Nanostructure of Plasmid DNA with Ionic Liquid [Bmim][PF₆]: Enhanced Efficiency in Bacterial Gene Transformation

The electrostatic interaction between the negatively charged phosphate groups of plasmid DNA and the cationic part of hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]­[PF₆]), initiates spontaneous self-assembly to form the functional nanostructures made up of DNA and ionic liquid (IL). These functional nanostructures were demonstrated as promising synthetic nonviral vectors for the efficient bacterial pGFP gene transformation in cells. In particular, the functional nanostructures that were made up of 1 μL of IL ([Bmim]­[PF₆]) and 1 μg of plasmid DNA can increase the transformation efficiency by 300–400% in microbial systems, without showing any toxicity for <i>E. coli</i> DH5α cells. ³¹P nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron (XPS) spectroscopic analysis revealed that the electrostatic interaction between negatively charged phosphate oxygen and cationic Bmim⁺ tends to initiate the self-assembly process. Thermogravimetric analysis of the DNA-IL functional nanostructures showed that these nanostructures consist of ∼16 wt % ionic liquid, which is considered to provide the stability to the plasmid DNA that eventually enhanced the transformation efficiency