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Published on: June 14, 2020
Concentrated ionic liquids for proteomics: Caveat emptor!
Thomas Goulden1, Iurii Bodachivskyi2, Matthew P Padula3
1University of Technology Sydney, School of Mathematical and Physical Sciences, 15 Broadway, Sydney, NSW 2007, Australia.
Insights
Concentrated ionic liquids (ILs) can dissolve previously insoluble proteins, aiding bioanalytical chemistry. However, high temperatures and long reaction times may degrade proteins, requiring careful control for proteomics applications.
Area of Science:
- Bioanalytical Chemistry
- Protein Chemistry
- Ionic Liquid Applications
Background:
- The application of concentrated ionic liquids (ILs) in protein bioanalysis is underexplored, with most studies using dilute solutions.
- Concentrated ILs possess unique properties that could enhance protein solubility and improve sample preparation for analysis.
Purpose of the Study:
- To systematically investigate the structure-activity relationship between ionic liquid structure and protein solubilization capacity.
- To evaluate the potential of concentrated ILs for dissolving previously insoluble protein analytes.
Main Methods:
- Bovine serum albumin (BSA) was dissolved in various ionic liquids.
- Protein dissolution was monitored over time using light microscopy.
- Protein integrity was assessed using SDS-PAGE.
Main Results:
- Hydrophilic ionic liquids demonstrated the highest protein solubilization capacity.
- Elevated temperatures generally improved protein solubility within a limited range.
- Prolonged exposure to higher temperatures and extended reaction times led to a reduction in protein molecular weight.
Conclusions:
- Concentrated ILs show promise for enhancing protein solubility in bioanalytical chemistry.
- Careful control of temperature and reaction time is crucial to maintain protein integrity, especially for proteomics.
- Further research is needed to fully understand the scope and limitations of concentrated ILs in protein analysis.
Abstract:
The use of concentrated ionic liquids (ILs) in the bioanalytical chemistry of proteins is sparse; typically, dilute aqueous IL solutions are used. Concentrated ILs have unique properties that may allow researchers to dissolve previously insoluble protein analytes, to increase the depth and robustness of sample preparation and the analysis of proteins. Previous research using concentrated ILs for this purpose is sparse and there is a need to systematically investigate the structure-activity relationship between the IL structure and its capacity to solubilise proteins. Here, bovine serum albumin was dissolved in various ionic liquids and monitored over time by light microscopy and SDS-PAGE. While qualitative, these measures provide a good estimate of, respectively, the dissolving power of an IL towards the given protein and the retained integrity of the protein. Hydrophilic ILs show the best solubilisation capacity and higher temperatures (in a restricted sense) improve the solubility of the protein. Higher temperatures and longer reaction times reduce the molecular weight of the protein, which could inhibit their applicability in proteomics, unless the conditions are judiciously controlled. Researchers should exercise caution when using concentrated ILs for protein analysis until the full scope and limitations are known, an aspect we are presently investigating.
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