Stabilizing G-quadruplex DNA and RNA structures with ionic liquids

Stabilizing DNA and RNA for long-term room-temperature storage is important for many biotechnological applications including oncology pharmaceuticals and mRNA-based vaccines (e.g. Covid vaccines). This poster shows that ionic liquids can improve the thermal stability of G-quadruplex DNA and RNA structures, and motivates further studies of ionic liquid-based materials for DNA / RNA stabilization

Heme Dissociation from Myoglobin in the Presence of the Zwitterionic Detergent N,N-Dimethyl-N-Dodecylglycine Betaine: Effects of Ionic Liquids

We have investigated myoglobin protein denaturation using the zwitterionic detergent Empigen BB (EBB, N,N-Dimethyl-N-dodecylglycine betaine). A combination of absorbance, fluorescence, and circular dichroism spectroscopic measurements elucidated the protein denaturation and heme dissociation from myoglobin. The results indicated that Empigen BB was not able to fully denature the myoglobin structure, but apparently can induce the dissociation of the heme group from the protein. This provides a way to estimate the heme binding free energy, ΔGdissociation. As ionic liquids (ILs) have been shown to perturb the myoglobin protein, we have investigated the effects of the ILs 1-butyl-3-methylimidazolium chloride (BMICl), 1-ethyl-3-methylimidazolium acetate (EMIAc), and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) in aqueous solution on the ΔGdissociation values. Absorbance experiments show the ILs had minimal effect on ΔGdissociation values when compared to controls. Fluorescence and circular dichroism data confirm the ILs have no effect on heme dissociation, demonstrating that low concentrations ILs do not impact the heme dissociation from the protein and do not significantly denature myoglobin on their own or in combination with EBB. These results provide important data for future studies of the mechanism of IL-mediated protein stabilization/destabilization and biocompatibility studies

Effects of Ionic Liquids on Metalloproteins.

In the past decade, innovative protein therapies and bio-similar industries have grown rapidly. Additionally, ionic liquids (ILs) have been an area of great interest and rapid development in industrial processes over a similar timeline. Therefore, there is a pressing need to understand the structure and function of proteins in novel environments with ILs. Understanding the short-term and long-term stability of protein molecules in IL formulations will be key to using ILs for protein technologies. Similarly, ILs have been investigated as part of therapeutic delivery systems and implicated in numerous studies in which ILs impact the activity and/or stability of protein molecules. Notably, many of the proteins used in industrial applications are involved in redox chemistry, and thus often contain metal ions or metal-associated cofactors. In this review article, we focus on the current understanding of protein structure-function relationship in the presence of ILs, specifically focusing on the effect of ILs on metal containing proteins

Proton transfer and esterification reactions in EMIMOAc-based acidic ionic liquids

Acetate-based ionic liquids (such as 1-ethyl-3-methylimidazolium acetate, EMIMOAc) have potential applications for CO2 absorption and electrochemical reduction, chemical separations and extractions, and Fischer esterification of alcohols, amines, and starch. Both strong and weak organic acids can be dissolved in EMIMOAc and yield interesting proton-rich acidic ionic liquid solutions. We have used GCMS vapor pressure measurements, spectroscopic methods, calorimetry, and viscosity/conductivity measurements to investigate the properties and reactions of various acids dissolved in EMIMOAc. Unique proton transfer and esterification reactions are observed in many of these acidic solutions with carboxylic acids or sulfonic acids as solutes. Some acids react with the acetate anion to produce acetic acid, which provides a measure of acid strength in ionic liquid solvents. In addition, we observed an esterification reaction that might involve the imidazolium cation and the acetate anion to yield methyl acetate

Synergistic interactions of ionic liquids and antimicrobials improve drug efficacy.

Combinations of ionic liquids (ILs) with antimicrobial compounds have been shown to produce synergistic activities in model liposomes. In this study, imidazolium chloride-based ILs with alkyl tail length variations are combined with commercially available, small-molecule antimicrobials to examine the potential for combinatorial and synergistic antimicrobial effects on P. aeruginosa, E. coli, S. aureus, and S. cerevisiae. The effects of these treatments in a human cell culture model indicate the cytotoxic limits of ILs paired with antimicrobials. The analysis of these ILs demonstrates that the length of the alkyl chain on the IL molecule is proportional to both antimicrobial activity and cytotoxicity. Moreover, the ILs which exhibit synergy with small-molecule antibiotics appear to be acting in a membrane permeabilizing manner. Collectively, results from these experiments demonstrate an increase in antimicrobial efficacy with specific IL + antimicrobial combinations on microbial cultures while maintaining low cytotoxicity in a mammalian cell culture model

Effects of Ionic Liquid Alkyl Chain Length on Denaturation of Myoglobin by Anionic, Cationic, and Zwitterionic Detergents

The unique electrochemical properties of ionic liquids (ILs) have motivated their use as solvents for organic synthesis and green energy applications. More recently, their potential in pharmaceutical chemistry has prompted investigation into their effects on biomolecules. There is evidence that some ILs can destabilize proteins via a detergent-like manner; however, the mechanism still remains unknown. Our hypothesis is that if ILs are denaturing proteins via a detergent-like mechanism, detergent-mediated protein unfolding should be enhanced in the presence of ILs. The properties of myoglobin was examined in the presence of a zwitterionic (N,N-dimethyl-N-dodecylglycine betaine (Empigen BB®, EBB)), cationic (tetradecyltrimethylammonium bromide (TTAB)), and anionic (sodium dodecyl sulfate (SDS)) detergent as well as ILs based on alkylated imidazolium chlorides. Protein structure was measured through a combination of absorbance, fluorescence, and circular dichroism (CD) spectroscopy: absorbance and CD were used to monitor heme complexation to myoglobin, and tryptophan fluorescence quenching was used as an indicator for heme dissociation. Notably, the detergents tested did not fully denature the protein but instead resulted in loss of the heme group. At low IL concentrations, heme dissociation remained a traditional, cooperative process; at high concentrations, ILs with increased detergent-like character exhibited a more complex pattern, which is most likely attributable to micellization of the ionic liquids or direct denaturation or heme dissociation induced by the ILs. These trends were consistent across all species of detergents. 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence was further used to characterize micelle formation in aqueous solutions containing detergent and ionic liquid. The dissociation thermodynamics show that EBB- and TTAB-induced dissociation of heme is not significantly impacted by room temperature ionic liquids (RTILs), whereas SDS-induced dissociation is more dramatically impacted by all RTILs examined. Together, these results indicate a complex interaction of detergents, likely based on headgroup charge, and the active component of RTILs to influence heme dissociation and potentially protein denaturation

Conductivity, Viscosity, Spectroscopic Properties of Organic Sulfonic Acid solutions in Ionic Liquids

Sulfonic acids in ionic liquids (ILs) are used as catalysts, electrolytes, and solutions for metal extraction. The sulfonic acid ionization states and the solution acid/base properties are critical for these applications. Methane sulfonic acid (MSA) and camphor sulfonic acid (CSA) are dissolved in several IL solutions with and without bis(trifluoromethanesulfonyl)imine (HTFSI). The solutions demonstrated higher conductivities and lower viscosities. Through calorimetry and temperature-dependent conductivity analysis, we found that adding MSA to the IL solution may change both the ion migration activation energy and the number of “free” charge carriers. However, no significant acid ionization or proton transfer was observed in the IL solutions. Raman and IR spectroscopy with computational simulations suggest that the HTFSI forms dimers in the solutions with an N-H-N “bridged” structure, while MSA does not perturb this hydrogen ion solvation structure in the IL solutions. CSA has a lower solubility in the ILs and reduced the IL solution conductivity. However, in IL solutions containing 0.4 M or higher concentration of HTFSI, CSA addition increased the conductivity at low CSA concentrations and reduced it at high concentrations, which may indicate a synergistic effect

The spectroscopy of jet-cooled porphyrins: an insight into the vibronic structure of the Q band

We will present resonant two-photon ionization spectra for meso-tetraphenylporphyrin, H2TPP, measured under isolated conditions. The polycrystalline compound was vaporized, in vacuo, using both thermal and laser desorption, and seeded into a supersonic expansion of an inert-carrier gas. The molecules remain largely intact in the gaseous phase. However, the two techniques for vaporizing H2TPP give different internal temperatures for the isolated substrate, with greater vibrational cooling achieved using laser desorption. A comparison of the peak positions and intensities in the resonant two-photon ionization spectra of thermal- and laser-desorbed molecules provides an insight into the vibrational structure of the Q band. In particular, the greater contribution made by electronic transitions originating from higher vibrational levels in the ground state of H2TPP is emphasized. We conclude that vibronic coupling in the ground electronic state plays an important role in a quantum-mechanical interpretation of the Q band