Critical Assessment of the Interaction between DNA and Choline AminoAcid Ionic Liquids: Evidences of Multimodal Binding and StabilityEnhancement

摘要

Long-term storage and stability of DNA is of paramount importance in biomedical applications. Ever since the emergence of ionic liquids (ILs) as alternate green solvents to aqueous and organic solvents, their exploration for the extraction and application of DNA need conscientious understanding of the binding characteristics and molecular interactions between IL and DNA. Choline amino acid ILs (CAAILs) in this regard seem to be promising due to their non-cytotoxic, completely biobased and environment-friendly nature. To unravel the key factors for the strength and binding mechanism of CAAILs with DNA, various spectroscopic techniques, molecular docking, and molecular dynamics simulations were employed in this work. UV–Vis spectra indicate multimodal binding of CAAILs with DNA, whereas dye displacement studies through fluorescence emission confirm the intrusion of IL molecules into the minor groove of DNA. Circular dichorism spectra show that DNA retains its native B-conformation in CAAILs. Both isothermal titration calorimetry and molecular docking studies provide an estimate of the binding affinity of DNA with CAAILs ≈ 4 kcal/mol. Theheterogeneity in binding modes of CAAIL-DNA system with evolutionof time was established by molecular dynamics simulations. Cholinecation while approaching DNA first binds at surface through electrostaticinteractions, whereas a stronger binding at minor groove occurs viavan der Waals and hydrophobic interactions irrespective of anionsconsidered in this study. We hope this result can encourage and guidethe researchers in designing new bio-ILs for biomolecular studiesin future.