Enhanced structural stability of insulin aspart in cholinium aminoate ionic liquids

Vidya Sundaram, Ramakrishnan Nagasundara Ramanan, Manikandan Selvaraj, R. Vijayaraghavan, Douglas R. MacFarlane, Chien Wei Ooi

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)


Cholinium aminoates [Ch][AA] have gained tremendous interest as a promising ionic liquid medium for the synthesis and storage of proteins. However, high alkalinity of [Ch][AA] limits its usage with pH-sensitive proteins. Here, we probed the structure, stability, and interactions of a highly unstable therapeutic protein, insulin aspart (IA), in a range of buffered [Ch][AA] (b-[Ch][AA]) using a combination of biophysical tools and in silico pipeline including ultraviolet-visible, fluorescence, and circular dichroism spectroscopies, dynamic light scattering measurements and molecular docking. b-[Ch][AA] used in the study differed in concentrations and their anionic counterparts. We reveal information on ion and residue specific solvent–protein interactions, demonstrating that the structural stability of IA was enhanced by a buffered cholinium prolinate. In comparison to the glycinate and alaninate anions, the hydrophilic prolinate anions established more hydrogen bonds with the residues of IA and provided a less polar environment that favours the preservation of IA in its active monomeric form, opening new opportunities for utilizing [Ch][AA] as storage medium.

Original languageEnglish
Pages (from-to)544-552
Number of pages9
JournalInternational Journal of Biological Macromolecules
Publication statusPublished - 31 May 2022


  • Cholinium aminoates
  • Insulin aspart
  • Ionic liquids
  • Protein stabilization
  • Protein-IL interaction

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