title: Solubilizing and Stabilizing Proteins in Anhydrous Ionic Liquids through Formation of Protein-Polymer Surfactant Nanoconstructs.
abstract: Nonaqueous biocatalysis is rapidly becoming a desirable tool for chemical and fuel synthesis in both the laboratory and industry. Similarly, ionic liquids are increasingly popular anhydrous reaction media for a number of industrial processes. Consequently, the use of enzymes in ionic liquids as efficient, environment-friendly, commercial biocatalysts is highly attractive. However, issues surrounding the poor solubility and low stability of enzymes in truly anhydrous media remain a significant challenge. Here, we demonstrate for the first time that engineering the surface of a protein to yield protein-polymer surfactant nanoconstructs allows for dissolution of dry protein into dry ionic liquids. Using myoglobin as a model protein, we show that this method can deliver protein molecules with near native structure into both hydrophilic and hydrophobic anhydrous ionic liquids. Remarkably, using temperature-dependent synchrotron radiation circular dichroism spectroscopy to measure half-denaturation temperatures, our results show that protein stability increases by 55 °C in the ionic liquid as compared to aqueous solution, pushing the solution thermal denaturation beyond the boiling point of water. Therefore, the work presented herein could provide a platform for the realization of biocatalysis at high temperatures or in anhydrous solvent systems.
authors.affiliation: Department of Chemical Engineering, Imperial College , London SW7 2AZ , United Kingdom.
authors.forename: Alex P S
authors.initials: AP
authors.lastname: Brogan
authors.affiliation: Department of Chemical Engineering, Imperial College , London SW7 2AZ , United Kingdom.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Hallett
mesh_terms: D055162:Biocatalysis; D057927:Hydrophobic and Hydrophilic Interactions; D052578:Ionic Liquids / Q000737:chemistry*; D008958:Models, Molecular; D009211:Myoglobin / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D052578:Ionic Liquids; D009211:Myoglobin; D011108:Polymers; D011506:Proteins; D012996:Solutions; D012997:Solvents; D013501:Surface-Active Agents; D014867:Water