Journal article
Structural Destabilization of Azurin by Imidazolium Chloride Ionic Liquids in Aqueous Solution
The journal of physical chemistry. B, v 123(32), pp 6933-6945
15 Aug 2019
PMID: 31335143
Abstract
Alkyl imidazolium chloride ionic liquids (ILs) have been used for numerous biochemical applications. Their hydrophobicity can be tuned by changing the alkyl chain length, and longer-chain ILs can form micelles in aqueous solution. We have investigated the effects of imidazolium chloride ILs on the structure and stability of azurin, which is a very stable Cu2+ redox protein with both α-helix and β-sheet domains. Temperature-dependent infrared (IR) and vibrational circular dichroism spectroscopy can provide secondary-structure-specific information about how the protein is affected, and temperature-jump transient IR measurements can quantify the IL-influenced unfolding dynamics. Using these techniques, we can quantify how azurin is destabilized by 1.0 M ILs in aqueous solution. The shorter, less hydrophobic ILs, 1-butyl-3-methylimidazolium chloride and 1-hexyl-3-methylimidazolium chloride likely interact with the α-helix domain and decrease protein melting temperature from 82 °C without IL to 55 °C and disturb the overall tertiary structure, resulting in a looser, more open shape. Thermodynamic analysis indicates that protein destabilization is due to increased unfolding entropy. 1-Octyl-3-methylimidazolium chloride [OMIM]Cl, which forms micelles in solution that may partially solvate the protein, has a more significant destabilizing effect, resulting in a melting temperature of 35 °C, larger unfolding entropy, and relaxation kinetics several orders of magnitude faster than with unperturbed azurin. The temperature-independence of the relaxation time constant suggests that in the presence of [OMIM]Cl, the protein folding potential energy surface has become very smooth.
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Details
- Title
- Structural Destabilization of Azurin by Imidazolium Chloride Ionic Liquids in Aqueous Solution
- Creators
- Arusha Acharyya - University of PennsylvaniaDavid DiGiuseppi - Drexel UniversityBrittany L Stinger - Rowan UniversityReinhard Schweitzer-Stenner - Drexel UniversityTimothy D Vaden - Rowan University
- Publication Details
- The journal of physical chemistry. B, v 123(32), pp 6933-6945
- Publisher
- American Chemical Society; Washington, DC
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- [Retired Faculty]
- Web of Science ID
- WOS:000481567500003
- Scopus ID
- 2-s2.0-85070690866
- Other Identifier
- 991019167961404721
InCites Highlights
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Physical