Hydrophobic hydration, hydrophobic forces and protein folding

a b s t r a c tHofmeister, specific ion effects, hydration and van der Waals forces at and between interfaces are factors that determine curvature and microstructure in self assembled aggregates of surfactants and lipids; and in microemulsions. Lipid and surfactant head group interactions and between aggregates vary enormously and are highly specific. They act on the hydrophilic side of a bilayer, micelle or other self assembled aggregate. It is only over the last three decades that the origin of Hofmeister effects has become generally understood. Knowledge of their systematics now provides much flexibility in designing nanostructured fluids.The other side of the coin involves equally specific forces. These (opposing) forces work on the hydrophobic side of amphiphilic interfaces. They are due to the interaction of hydrocarbons and other "oils" with hydrophobic tails of surfactants and lipids. The specificity of oleophilic solutes in microemulsions and lipid membranes provides a counterpoint to Hofmeister effects and hydration. Together with global packing constraints these effects determine microstructure.Another factor that has hardly been recognised is the role of dissolved gas. This introduces further, qualitative changes in forces that prescribe microstructure.The systematics of these effects and their interplay are elucidated. Awareness of these competing factors facilitates formulation of self assembled nanostructured fluids. New and predictable geometries that emerge naturally provide insights into a variety of biological phenomena like anaesthetic and pheromone action and transmission of the nervous impulse (see Part 2).

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“…This has been very nicely argued by Henry [15,108] and through the extensive work of Philippa Wiggins [114][115][116].…”

Section: Hydration Hydrophobicity and Other Known Unknownsmentioning

confidence: 69%

Two sides of the coin. Part 1. Lipid and surfactant self-assembly revisited

Ninham

Larsson

Nostro

2017

Colloids and Surfaces B: Biointerfaces

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“…Thus Na 2 SO 4 , NaCl, and NaClO 4 were selected for their increasing capacity to favor LDW domains formation. Moreover, two ammonium salts were studied, NH 4 NO 3 and (NH 4 ) 2 SO 4 , as the first one should demolish LDW domains owing to the competitive behavior of cation and anion, while the second one should stabilize LDW [9].…”

Section: Use Of DL For Analysis Of Watermentioning

confidence: 99%

“…Moreover, populations of LDW may have a role in the hydrophobic interaction, which drives protein folding. Since neutral salts, which stabilize LDW, also stabilize the folded conformation of proteins, it seems probable that the folded protein needs the presence of LDW, and that unfolding follows its destruction [9].…”

mentioning

confidence: 99%

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Delayed luminescence: a novel technique to obtain new insights into water structure

et al. 2012

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Fully understanding the structure of water is a crucial point in biophysics because this liquid is essential in the operation of the engines of life. Many of its amazing anomalies seem to be tailored to support biological processes and, during about a century, several models have been developed to describe the water structuring. In particular, a theory assumes that water is a mixture of domains constituted by two distinct and interconverting structural species, the low-density water (LDW) and the high-density water (HDW). According to this theory, by using some particular solutes or changing the water temperature, it should be possible to modify the equilibrium between the two species, changing in this way the water behavior in specific biological processes, as in governing the shape and stability of the structures of proteins. In this work, we assess the possibility of obtaining information on the structures induced in water by specific salts or by temperature by measuring the delayed luminescence (DL) of some salt solutions and of water in the super-cooled regime. Previous works have demonstrated that the delayed luminescence of a system is correlated with its dynamic ordered structures. The results show significant DL signals only when the formation of LDW domains is expected. The measurement reveals a similar activation energy for the domains both in aqueous salt solutions and super-cooled water. It is worth noting that the time trend of DL signals suggests the existence of structures unusually long-lasting in time, up to the microsecond range.

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“…[1][2][3] Based on their effects on the water structure, ions can be classified as kosmotropes (water structure-making ions), chaotropes (water structure-breaking ions), and borderline ions (little effect on the water structure), 4 while the order of ion kosmotropicity has also been known as the Hofmeister series. 5,6 It is well established that strong kosmotropic anions stabilize proteins while strong kosmotropic cations destabilize them.…”

Section: Introductionmentioning

confidence: 99%