Protein solubilising and stabilising ionic liquids

Fujita, Kyoko; MacFarlane, Douglas R.; Forsyth, Maria

doi:10.1039/b508238b

Cited by 453 publications

(431 citation statements)

References 22 publications

(36 reference statements)

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“…Fujita et al 30 have recently reported that the protein cytochrome c is remarkably stablilized in solution in a nontoxic dihydrogen phosphate IL, and we have found 31 that lysozyme in It is well-known from standard biological concentration solution studies that each protein has pH range in which its native state is most preferred and that deviations from that pH range can affect its folding energy and its stability against such undesirable behavior as aggregation, and recently, fibrillization. It might be expected that the proton activity of the solvent will exert a strong effect on the stability of proteins in the ionic liquid protective solution, and this is verified by our findings, 32 which are shown in Figure 12.…”

Section: Proton Activity and Protein Stabilization In Pilsmentioning

confidence: 52%

Parallel Developments in Aprotic and Protic Ionic Liquids: Physical Chemistry and Applications

2007

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This Account covers research dating from the early 1960s in the field of low-melting molten salts and hydrates,which has recently become popular under the rubric of "ionic liquids". It covers understanding gained in the principal author's laboratories (initially in Australia, but mostly in the U.S.A.) from spectroscopic, dynamic, and thermodynamic studies and includes recent applications of this understanding in the fields of energy conversion and biopreservation. Both protic and aprotic varieties of ionic liquids are included, but recent studies have focused on the protic class because of the special applications made possible by the highly variable proton activities available in these liquids.In this Account, we take a broad view of ionic liquids (using the term in its current sense of liquids comprised of ions and melting below 100°C). We include, along with the general cases of organic cation systems, liquids in which common inorganic cations (like Mg 2+ and Ca 2+ ) strongly bind a hydration or solvation shell and then behave like large cation systems and melt below 100°C.We will try to organize a wide variety of measurements on low-melting ionic liquid systems into a coherent body of knowledge that is relevant to the ionic liquid field as it is currently developing.Under the expanded concept of the field, ionic liquid studies commenced in the Angell laboratory in 1962 with a study of the transport properties of the hydrates of Mg(NO 3 ) 2 and Ca(NO 3 ) 2 . These were described as melts of "large weak-field cations" 1 and their properties correlated with those of normal anhydrous molten salts via their effective cation radii, the sum of the normal radius plus one water molecule diameter. This notion was followed in 1966 with a full study under the title "A new class of molten salt mixtures" in which the hydrated cations were treated as independent cation species. The large cations mixed ideally with ordinary inorganic cations such as Na + and K + , to give solutions in which such cohesion indicators as the glass transition temperature, T g , changed linearly with composition. The concept proved quite fruitful, and a field ("hydrate melts" or "solvate melts") developed in its wake in which asymmetric anions like SCN -and NO 2 -were used with solvated cations to create a very wide range of systems that were liquid at room temperature, while remaining ionic in their general properties.The validity of the molten salt analogy was given additional conviction by the observation that transition metal ions such as Ni(II) and Co(II) could be found in the complex anion states NiCl 4 2-and CoCl 4 2-when added to the "hydrate melt" chlorides. 2 Of special interest here was the observation 3 of extreme downfield NMR proton chemical shifts of hydrate protons when the hydrated cation was Al 3+ . These lay much further downfield than did the protons in strong mineral acids at the same concentration, leading to the design of solutions of highly acidic character from salts that would usually be considered neutral. Inde...

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Section: Proton Activity and Protein Stabilization In Pilsmentioning

confidence: 52%

Parallel Developments in Aprotic and Protic Ionic Liquids: Physical Chemistry and Applications

2007

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“…Ionic liquids have attracted much interest recently as solvents for biomolecules because they are nonaqueous solvents that are able to promote the self-assembly of amphiphiles (29), and they appear to stabilize protein function (30,31), and some can promote, inhibit, or solubilize amyloid fibrils (32)(33)(34). To date, only high concentrations of strong acids such as formic acid and TFA have been reported to depolymerize rodlets to the monomeric form (6).…”

Section: Resultsmentioning

confidence: 99%

Recruitment of Class I Hydrophobins to the Air:Water Interface Initiates a Multi-step Process of Functional Amyloid Formation

Morris

Ren

Macindoe

et al. 2011

Journal of Biological Chemistry

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Class I fungal hydrophobins form amphipathic monolayers composed of amyloid rodlets. This is a remarkable case of functional amyloid formation in that a hydrophobic:hydrophilic interface is required to trigger the self-assembly of the proteins. The mechanism of rodlet formation and the role of the interface in this process have not been well understood. Here, we have studied the effect of a range of additives, including ionic liquids, alcohols, and detergents, on rodlet formation by two class I hydrophobins, EAS and DewA. Although the conformation of the hydrophobins in these different solutions is not altered, we observe that the rate of rodlet formation is slowed as the surface tension of the solution is decreased, regardless of the nature of the additive. These results suggest that interface properties are of critical importance for the recruitment, alignment, and structural rearrangement of the amphipathic hydrophobin monomers. This work gives insight into the forces that drive macromolecular assembly of this unique family of proteins and allows us to propose a three-stage model for the interface-driven formation of rodlets.Class I hydrophobins are a family of small amphipathic proteins that are produced by filamentous fungi in a monomeric form but are able to self-assemble into amphipathic monolayers composed of amyloid-like structures known as rodlets (1-3). The polymerization of the hydrophobins occurs on contact with a hydrophobic:hydrophilic interface, such as an air:water boundary or when hydrophobins are secreted from the spores and come into contact with the air. Members of the hydrophobin family are characterized by the presence of four disulfide bonds. The amphipathic nature of hydrophobins drives them to the surface of solutions, where they reduce the surface tension (1).Some of the functional roles of the class I hydrophobins include acting as a surfactant at the air:water boundary to reduce the surface tension, which is a barrier to aerial growth of hyphae, and also to form a robust protein coat on spores. This coating provides a hydrophobic external surface that resists wetting and thus facilitates spore dispersal in air (4 -6). The class I hydrophobin rodlets share many of the structural characteristics of amyloid fibrils; formation of the insoluble, fibrillar rodlets is accompanied by conformational change to an ordered cross-␤-secondary structure form and the polymerized rodlets, but not the monomeric form of the protein, bind to the dye thioflavin T (ThT) 4 (2, 7, 8). However, in contrast to other amyloid fibrils, which can often be solubilized by treatment with denaturants such as guanidine hydrochloride or solvents such as dimethyl sulfoxide (9), treatment with acids such as formic and TFA has been reported to be the only method capable of depolymerizing hydrophobin rodlets and regenerating the monomeric form of the hydrophobin proteins in solution (10,11). This is similar to the curli and tafi fibrils produced by bacteria, which have been shown to be functional amyloid and which also req...

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“…[19][20][21][22] In addition, they act as solvents or catalysts for various organic reactions. 23,24 Similarly, RTILs with the hydroxyl groups have CO2 absorption, [25][26][27][28][29] and cellulose/protein dissolution abilities.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical and Acid-base Properties of a Series of 2-Hydroxyethylammonium-based Protic Ionic Liquids

et al. 2012

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Protein solubilising and stabilising ionic liquids

Abstract: We report a family of biocompatible ionic liquids (ILs) which are able to dissolve significant amounts of proteins such as cytochrome c and in which ATR-FTIR spectroscopy results show retention of secondary structure to extreme temperatures.

Cited by 453 publications

References 22 publications

Parallel Developments in Aprotic and Protic Ionic Liquids: Physical Chemistry and Applications

Parallel Developments in Aprotic and Protic Ionic Liquids: Physical Chemistry and Applications

Recruitment of Class I Hydrophobins to the Air:Water Interface Initiates a Multi-step Process of Functional Amyloid Formation

Physicochemical and Acid-base Properties of a Series of 2-Hydroxyethylammonium-based Protic Ionic Liquids

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