Molecular dynamics simulation of AOT reverse micelles

Brodskaya, E. N.; Mudzhikova, G. V.

doi:10.1080/00268970601012728

Cited by 41 publications

(45 citation statements)

References 24 publications

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“…53,54 More recent work 8,45 suggests that reverse micelles are less spherical than originally presumed. The simulations reported here represent a single monodisperse interpretation of the water loading of w 0 = 6, with 474 water molecules and 80 AOT molecules.…”

Section: B Interpretations Of Water Loading and Limitations Of Sphermentioning

confidence: 99%

Protein folding in a reverse micelle environment: The role of confinement and dehydration

Martinez

Domı́nguez

Rivera

et al. 2011

The Journal of Chemical Physics

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Characterization of the molecular interactions that stabilize the folded state of proteins including hydrogen bond formation, solvation, molecular crowding, and interaction with membrane environments is a fundamental goal of theoretical biophysics. Inspired by recent experimental studies by Gai and co-workers, we have used molecular dynamics simulations to explore the structure and dynamics of the alanine-rich AKA 2 peptide in bulk solution and in a reverse micelle environment. The simulated structure of the reverse micelle shows substantial deviations from a spherical geometry. The AKA 2 peptide is observed to (1) remain in a helical conformation within a spherically constrained reverse micelle and (2) partially unfold when simulated in an unconstrained reverse micelle environment, in agreement with experiment. While aqueous solvation is found to stabilize the N-and C-termini random coil portions of the peptide, the helical core region is stabilized by significant interaction between the nonpolar surface of the helix and the aliphatic chains of the AOT surfactant. The results suggest an important role for nonpolar peptide-surfactant and peptide-lipid interactions in stabilizing helical geometries of peptides in reverse micelle environments.

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Section: B Interpretations Of Water Loading and Limitations Of Sphermentioning

confidence: 99%

Protein folding in a reverse micelle environment: The role of confinement and dehydration

Martinez

Domı́nguez

Rivera

et al. 2011

The Journal of Chemical Physics

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“…The uncertainty about RM size is especially problematic when performing molecular dynamics (MD) simulations for insight into the structure and organization of RMs because the number of molecular components in most simulations is fixed. 14 The question of RM size remains unresolved despite numerous MD simulation studies with continuum solvent, 15–17 coarse-grained surfactant, 18–22 and all-atom models. 13,23 Indeed, RM simulations of W 0 = 7.5 have been recently described with as few as 70 AOT molecules per RM, 24 ( n AOT ) and as many as 106.…”

Section: Introductionmentioning

confidence: 99%

The Size of AOT Reverse Micelles

Eskici

Axelsen

2016

J. Phys. Chem. B

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Reverse micelles (RMs) made from water and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) are commonly studied experimentally as models of aqueous microenvironments. They are small enough for individual RMs to also be studied by molecular dynamics (MD) simulation, which yields detailed insight into their structure and properties. Although RM size is determined by the water loading ratio (i.e. the molar ratio of water to AOT), experimental measurements of RM size are imprecise and inconsistent, which is problematic when seeking to understand the relationship between water loading ratio and RM size, and when designing models for study by MD simulation. Therefore, a systematic study of RM size was performed by MD simulation with the aims of determining the size of an RM for a given water loading ratio, and of reconciling the results with experimental measurements. Results for a water loading ratio of 7.5 indicate that the interaction energy between AOT anions and other system components is at a minimum when there are 62 AOT anions in each RM. The minimum is due to a combination of attractive and repulsive electrostatic interactions that vary with RM size and the dielectric effect of available water. Overall, the results agree with a detailed analysis of previously published experimental data over a wide range of water loading ratios, and help reconcile seemingly discrepant experimental results. In addition, water loss and gain from an RM is observed and the mechanism of water exchange is outlined. This kind of RM model, which faithfully reproduces experimental results, is essential for reliable insights into the properties of RM-encapsulated materials.

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“…In analysing the micelle forms resulting from the different PCs quantitatively, we follow the example set by previous computational studies of RMs 22,23,29 and calculate the semiaxes lengths a, b, and c from the principal moments of inertia by assuming that the RMs were ellipsoids of uniform density. For ellipsoids, the relations between semiaxes and principal moments of inertia are given by equations…”

Section: Systemmentioning

confidence: 99%

“…Although gaining popularity, so far the computational investigation of RM systems has been restricted to only a handful of systems. In particular, ternary systems composed of water, supercritical carbon dioxide, and acid functionalized perfluoroalkane or perfluoropolyether surfactants, [15][16][17][18][19][20] as well as, systems composed of water, apolar solvent (oil) and Aerosol OT (AOT) [21][22][23][24][25][26][27][28][29][30][31] have been characterized. Additionally, alkyl-PEG 32 and malonamide derived surfactant 33 systems have been studied by computer simulations.…”

Section: Introductionmentioning

confidence: 99%

Phosphatidylcholine reverse micelles on the wrong track in molecular dynamics simulations of phospholipids in an organic solvent

Vierros

Sammalkorpi

2015

The Journal of Chemical Physics

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Here, we examine a well-characterized model system of phospholipids in cyclohexane via molecular dynamics simulations using a force field known for reproducing both phospholipid behavior in water and cyclohexane bulk properties to a high accuracy, CHARMM36, with the aim of evaluating the transferability of a force field parametrization from an aqueous environment to an organic solvent. We compare the resulting reverse micelles with their expected experimental shape and size, and find the model struggles with reproducing basic, experimentally known reverse micellar structural characteristics for common phosphadidylcholine lipids such as 1,2-dipalmitoyl-snglycero-3-phosphatidylcholine (DPPC), 1,2-dioleyl-sn-glycero-3-phosphatidylcholine (DOPC), and 1,2-dilinoleyl-sn-glycero-3-phosphatidylcholine (DLPC) in cyclohexane solvent. We find evidence that the deviation from the experimental behavior originates from an underestimation of the lipid tail-cyclohexane interaction in the model. We compensate for this, obtain reverse micellar structures within the experimentally expected range, and characterize these structurally in molecular detail. Our findings indicate extra caution and verification of model applicability is warranted in simulational studies employing standard biomolecular models outside the usual aqueous environment. C 2015 AIP Publishing LLC. [http://dx

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Molecular dynamics simulation of AOT reverse micelles

Cited by 41 publications

References 24 publications

Protein folding in a reverse micelle environment: The role of confinement and dehydration

Protein folding in a reverse micelle environment: The role of confinement and dehydration

The Size of AOT Reverse Micelles

Phosphatidylcholine reverse micelles on the wrong track in molecular dynamics simulations of phospholipids in an organic solvent

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