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Chen X, Yuan S, Qiao M, Jin X, Chen J, Guo L, Su J, Qu DH, Zhang Z. Exploring the Depth-Dependent Microviscosity inside a Micelle Using Butterfly-Motion-Based Fluorescent Probes. J Am Chem Soc 2023; 145:26494-26503. [PMID: 38000910 DOI: 10.1021/jacs.3c11482] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Abstract
The viscosity distribution of micellar interiors from the very center to the outer surface is dramatically varied, which has been distinguished in theoretical models, yet it remains highly challenging to quantify this issue experimentally. Herein, a series of fluorophore-substituted surfactants DPAC-Fn (n = 3, 5, 7, 9, 11, 13, and 15) are developed by functionalizing the different alkyl-trimethylammonium bromides with the butterfly motion-based viscosity sensor, N,N'-diphenyl-dihydrodibenzo[a,c]phenazine (DPAC). The immersion depth of DPAC units of DPAC-Fn in cetrimonium bromide (C16TAB) micelles depends on the alkyl chain lengths n. From deep (n = 15) to shallow (n = 3), DPAC-Fn in C16TAB micelles exhibits efficient viscosity-sensitive dynamic multicolor emissions. With external standards for quantification, the viscosity distribution inside a C16TAB micelle with the size of ∼4 nm is changed seriously from high viscosity (∼190 Pa s) in the core center to low viscosity (∼1 Pa s) near the outer surface. This work provides a tailored approach for powerful micelle tools to explore the depth-dependent microviscosity of micellar interiors.
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Affiliation(s)
- Xuanying Chen
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Mengyuan Qiao
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xin Jin
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jiacheng Chen
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Lifang Guo
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jianhua Su
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Da-Hui Qu
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Zhiyun Zhang
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
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Bothe A, Zouni A, Müh F. Refined definition of the critical micelle concentration and application to alkyl maltosides used in membrane protein research. RSC Adv 2023; 13:9387-9401. [PMID: 36968053 PMCID: PMC10031436 DOI: 10.1039/d2ra07440k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/12/2023] [Indexed: 03/24/2023] Open
Abstract
The critical micelle concentration (CMC) of nonionic detergents is defined as the breaking point in the monomer concentration as a function of the total detergent concentration, identified by setting the third derivate of this function to zero. Combined with a mass action model for micelle formation, this definition yields analytic formulae for the concentration ratio of monomers to total detergent at the CMC and the relationship between the CMC and the free energy of micellization g mic. The theoretical breaking point is shown to coincide with the breaking point of the experimental titration curve, if the fluorescence enhancement of 8-anilino-1-naphthalene-sulfonic acid (ANS) or a similar probe dye is used to monitor micelle formation. Application to a series of n-alkyl-β-d-maltosides with the number of carbon atoms in the alkyl chain ranging from 8 to 12 demonstrates the good performance of a molecular thermodynamic model, in which the free energy of micellization is given by g mic = σΦ + g pack + g st. In this model, σ is a fit parameter with the dimension of surface tension, Φ represents the change in area of hydrophobic molecular surfaces in contact with the aqueous phase, and g pack and g st are contributions, respectively, from alkyl chain packing in the micelle interior and steric repulsion of detergent head groups. The analysis of experimental data from different sources shows that varying experimental conditions such as co-solutes in the aqueous phase can be accounted for by adapting only σ, if the co-solutes do not bind to the detergent to an appreciable extent. The model is considered a good compromise between theory and practicability to be applied in the context of in vitro investigations of membrane proteins.
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Affiliation(s)
- Adrian Bothe
- Institut für Biologie, Humboldt Universität zu Berlin Leonor-Michaelis-Haus, Philippstrasse 13 D-10095 Berlin Germany
| | - Athina Zouni
- Institut für Biologie, Humboldt Universität zu Berlin Leonor-Michaelis-Haus, Philippstrasse 13 D-10095 Berlin Germany
| | - Frank Müh
- Institut für Theoretische Physik, Johannes Kepler Universität Linz Altenberger Strasse 69 A-4040 Linz Austria
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Subbotin V, Fiksel G. Exploring the Lipid World Hypothesis: A Novel Scenario of Self-Sustained Darwinian Evolution of the Liposomes. ASTROBIOLOGY 2023; 23:344-357. [PMID: 36716277 PMCID: PMC9986030 DOI: 10.1089/ast.2021.0161] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 12/03/2022] [Indexed: 06/18/2023]
Abstract
According to the Lipid World hypothesis, life on Earth originated with the emergence of amphiphilic assemblies in the form of lipid micelles and vesicles (liposomes). However, the mechanism of appearance of the information molecules (ribozymes/RNA) accompanying that process, considered obligatory for Darwinian evolution, is unclear. We propose a novel scenario of self-sustained Darwinian evolution of the liposomes driven by ever-present natural phenomena: solar UV radiation, day/night cycle, gravity, and the formation of liposomes in an aqueous media. The central tenet of this scenario is the liposomes' encapsulation of the heavy solutes, followed by their gravitational submerging in the water. The submerged liposomes, being protected from the damaging UV radiation, acquire the longevity necessary for autocatalytic replication of amphiphiles, their mutation, and the selection of those amphiphilic assemblies that provide the greatest membrane stability. These two sets of adaptive compositional information (heavy content and amphiphilic assemblies design) generate a population of liposomes with self-replication/reproduction properties, which are amendable to mutation, inheritance, and selection, thereby establishing Darwinian progression. Temporary and spatial expansion of this liposomal population will provide the basis for the next evolutionary step-a transition of accidentally entrapped RNA precursor molecules into complex functional molecules, such as ribozymes/RNA.
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Affiliation(s)
- Vladimir Subbotin
- Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gennady Fiksel
- Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan, USA
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Molugu TR, Thurmond RL, Alam TM, Trouard TP, Brown MF. Phospholipid headgroups govern area per lipid and emergent elastic properties of bilayers. Biophys J 2022; 121:4205-4220. [PMID: 36088534 PMCID: PMC9674990 DOI: 10.1016/j.bpj.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 08/10/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022] Open
Abstract
Phospholipid bilayers are liquid-crystalline materials whose intermolecular interactions at mesoscopic length scales have key roles in the emergence of membrane physical properties. Here we investigated the combined effects of phospholipid polar headgroups and acyl chains on biophysical functions of membranes with solid-state 2H NMR spectroscopy. We compared the structural and dynamic properties of phosphatidylethanolamine and phosphatidylcholine with perdeuterated acyl chains in the solid-ordered (so) and liquid-disordered (ld) phases. Our analysis of spectral lineshapes of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-d62) and 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine (DPPC-d62) in the so (gel) phase indicated an all-trans rotating chain structure for both lipids. Greater segmental order parameters (SCD) were observed in the ld (liquid-crystalline) phase for DPPE-d62 than for DPPC-d62 membranes, while their mixtures had intermediate values irrespective of the deuterated lipid type. Our results suggest the SCD profiles of the acyl chains are governed by methylation of the headgroups and are averaged over the entire system. Variations in the acyl chain molecular dynamics were further investigated by spin-lattice (R1Z) and quadrupolar-order relaxation (R1Q) measurements. The two acyl-perdeuterated lipids showed distinct differences in relaxation behavior as a function of the order parameter. The R1Z rates had a square-law dependence on SCD, implying collective mesoscopic dynamics, with a higher bending rigidity for DPPE-d62 than for DPPC-d62 lipids. Remodeling of lipid average and dynamic properties by methylation of the headgroups thus provides a mechanism to control the actions of peptides and proteins in biomembranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | | | - Todd M Alam
- Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico
| | - Theodore P Trouard
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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Denk P, El Maangar A, Prévost S, Silva W, Gschwind R, Zemb T, Kunz W. Cloud point, auto-coacervation, and nematic ordering of micelles formed by ethylene oxide containing carboxylate surfactants. J Colloid Interface Sci 2022; 621:470-488. [PMID: 35483179 DOI: 10.1016/j.jcis.2022.04.046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 10/18/2022]
Abstract
HYPOTHESIS In a recent paper, we determined the phase behavior of an aqueous solution of octyl ether octaethylene oxide carboxylic acid ([H+][C8E8c-], Akypo™ LF2) and with partial replacement of H+ by Na+ and Ca2+. It was found that even the neat surfactants are liquid at room temperature and that they form only direct micelles for any aqueous content and over large temperature ranges. The aim of the present work was to find an explanation for the clouding in these systems as well as for the coacervation observed at very low surfactant content. We expected that very similar phase diagrams would be found for a full replacement of H+ by the mentioned ions. EXPERIMENTS We established the respective phase diagrams of the above-mentioned salts in water and determined the structures of the occurring phases in detail with small-and wide-angle X-ray scattering, small-angle neutron scattering, dynamic light scattering, heat flux differential scanning calorimetry, as well as surface tension, ESI-MS, and NMR experiments. FINDINGS To our surprise, we discovered a new type of nematic phase between an isotropic and a hexagonal phase. Based on the complete description of all occurring phases both in the acidic and the charged surfactant systems, we were able to design a coherent and unified picture of all these phases, including the auto-coacervation at low surfactant concentration, the non-conventional clouding at high temperatures, the unusual liquid crystalline phases in a small domain at high surfactant concentrations, and the Lβ phase at low temperatures and at very low water content. It turned out that all phenomena are a consequence of the subtle interplay between a) the packing constraint due to the very large head-group, b) the relatively small hydrocarbon chain and c) the tunable electrostatic interactions versus entropy.
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Affiliation(s)
- Patrick Denk
- Institute of Physical and Theoretical Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | | | - Sylvain Prévost
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Wagner Silva
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Ruth Gschwind
- Institute of Organic Chemistry, University of Regensburg, D-93053 Regensburg, Germany
| | - Thomas Zemb
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
| | - Werner Kunz
- Institute of Physical and Theoretical Chemistry, University of Regensburg, D-93053 Regensburg, Germany.
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6
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La Mesa C, Risuleo G. Surface Activity and Efficiency of Cat-Anionic Surfactant Mixtures. Front Chem 2022; 9:790873. [PMID: 34970533 PMCID: PMC8712687 DOI: 10.3389/fchem.2021.790873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 10/27/2021] [Indexed: 11/13/2022] Open
Abstract
The surface activity of surfactant mixtures is critically analyzed. Cat-anionic systems, in which two ionic species are mixed in non-stoichiometric ratios, are considered. With respect to the solution behavior, where a substantial decrease of cmc is met compared to the pure components, a moderate effect on surface tension, γ, occurs. Compared to the pure species, the decrease of surface tension for such mixtures is not significant, and no clear dependence on the mole fraction anionic/cationic is met. The surface tension is grossly constant in the whole concentration range. Conversely, the interaction parameter for surfaces, βsurf (calculated by the regular solution theory), is more negative than that for micelle formation, βmic. This fact suggests that the desolvation of polar heads of the two species at interfaces is largely different. Very presumably, the underlying rationale finds origin in the sizes and solvation of both polar head groups.
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Affiliation(s)
- Camillo La Mesa
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
| | - Gianfranco Risuleo
- Department of Biology and Biotechnologies Charles Darwin, Sapienza University of Rome, Rome, Italy
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Analytical modeling of micelle growth. 4. Molecular thermodynamics of wormlike micelles from ionic surfactants: Theory vs. experiment. J Colloid Interface Sci 2021; 584:561-581. [DOI: 10.1016/j.jcis.2020.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 12/20/2022]
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8
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Muthusivarajan R, Allen WJ, Pehere AD, Sokolov KV, Fuentes D. Role of alkylated residues in the tetrapeptide self-assembly-A molecular dynamics study. J Comput Chem 2020; 41:2634-2640. [PMID: 32930440 PMCID: PMC7983104 DOI: 10.1002/jcc.26419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/05/2020] [Accepted: 08/28/2020] [Indexed: 12/17/2022]
Abstract
Designing peptide sequences that self-assemble into well-defined nanostructures can open a new venue for the development of novel drug carriers and molecular contrast agents. Current approaches are often based on a linear block-design of amphiphilic peptides where a hydrophilic peptide chain is terminated by a hydrophobic tail. Here, a new template for a self-assembling tetrapeptide (YXKX, Y = tyrosine, X = alkylated tyrosine, K = lysine) is proposed with two distinct sides relative to the peptide's backbone: alkylated hydrophobic residues on one side and hydrophilic residues on the other side. Using all-atom molecular dynamics simulations, the self-assembly pathway of the tetrapeptide is analyzed for two different concentrations. At both concentrations, tetrapeptides self-assembled into a nanosphere structure. The alkylated tyrosines initialize the self-assembly process via a strong hydrophobic effect and to reduce exposure to the aqueous solvent, they formed a hydrophobic core. The hydrophilic residues occupied the surface of the self-assembled nanosphere. Ordered arrangement of tetrapeptides within the nanosphere with the backbone hydrogen bonding led to a beta sheet formation. Alkyl chain length constrained the size and shape of the nanosphere. This study provides foundation for further exploration of self-assembling structures that are based on peptides with hydrophobic and hydrophilic moieties located on the opposite sides of a peptide backbone.
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Affiliation(s)
| | - William J. Allen
- Texas Advanced Computing Center, The University of Texas at Austin, Austin, Texas
| | - Ashok D. Pehere
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Konstantin V. Sokolov
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
- Department of Bioengineering, Rice University, Houston, Texas
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
| | - David Fuentes
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
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Abstract
Proteins with a high degree of sequence similarity representing different structures provide a key to understand how protein sequence codes for 3D structure. An analysis using the fuzzy oil drop model was carried out on two pairs of proteins with different secondary structures and with high sequence identities. It has been shown that distributions of hydrophobicity for these proteins are approximated well using single 3D Gaussian function. In other words, the similar sequences fold into different 3D structures, however, alternative structures also have symmetric and monocentric hydrophobic cores. It should be noted that a significant change in the helical to beta-structured form in the N-terminal section takes places in the fragment much preceding the location of the mutated regions. It can be concluded that the final structure is the result of a complicated synergy effect in which the whole chain participates simultaneously.
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10
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Rosenholm JB. Critical evaluation of models for self-assembly of short and medium chain-length surfactants in aqueous solutions. Adv Colloid Interface Sci 2020; 276:102047. [PMID: 31954873 DOI: 10.1016/j.cis.2019.102047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 10/25/2022]
Abstract
During numerous visits to our Laboratory professor Johannes (Hans) Lyklema emphasized the importance of a holistic view on thermodynamics. In order to fulfill this aim he assembled the monumental Fundamentals of Interface and Colloid Science series. The basic state functions (internal energy, enthalpy and free energies) are interrelated by Gibbs and Helmholtz relationships. First-order phase transitions are characterized by first-order state variables (temperature, pressure, entropy, volume). Interactions are, however best expressed by second-order partial derivatives (compressibility, heat capacity and expansivity). They are related to the first-order state variables by relaxation contributions quantifying the degree of cooperativity of self-assembly processes leading to phase separation. In particular they exhibit the limit when phase transitions are changed to second-order processes. This was the focus of my first review dedicated to the memory of professor Lyklema, "Characterization of van der Waals type bimodal,- lambda,- meta- and spinodal phase transitions in liquid mixtures, solid suspensions and thin films" (ACIS 253 (2018) 66). In the present review the attention is placed on short and medium chain-length surfactant self-assembly in aqueous solutions without additives (salts or solubilizates). The dependence of state functions described above on concentration, temperature and pressure is compared to corresponding dynamic molecular processes occurring on different time, frequency and length scales including structure analysis. It is convincingly shown that Hartley-Tanford space filled spherical anhydrous micelle core - polar shell model designed for long chain-length surfactants (cmc < 0.01 mol/dm3, N > 50) cannot be enforced on short and medium chain-length surfactant non-sperical micelles (cmc close to unity, N < 20). Moreover, it is shown that a proper validity evaluation of proposed models for micelle formation is seriously undermined by their application to only a narrow concentration range near critical micelle concentration (cmc). When successful each model should characterize all self-assembly processes occurring (also at limiting association concentration, lac, at second critical concentration, 2cc and at third critical concen-tration, 3cc) within the entire concentration range of thermodynamically stable surfactant solutions. All other self-assembly processes except micelle formation are rarely considered. The pre-micelle formation at lac is, for example omitted as deviations from presented models. The reviewed reports are therefore selected on the basis of maximum investigated concentration range and of largest possible number of homologues.
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The Amyloid as a Ribbon-Like Micelle in Contrast to Spherical Micelles Represented by Globular Proteins. Molecules 2019; 24:molecules24234395. [PMID: 31816829 PMCID: PMC6930452 DOI: 10.3390/molecules24234395] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/27/2019] [Accepted: 11/29/2019] [Indexed: 01/18/2023] Open
Abstract
Selected amyloid structures available in the Protein Data Bank have been subjected to a comparative analysis. Classification is based on the distribution of hydrophobicity in amyloids that differ with respect to sequence, chain length, the distribution of beta folds, protofibril structure, and the arrangement of protofibrils in each superfibril. The study set includes the following amyloids: Aβ (1-42), which is listed as Aβ (15-40) and carries the D23N mutation, and Aβ (11-42) and Aβ (1-40), both of which carry the E22Δ mutation, tau amyloid, and α-synuclein. Based on the fuzzy oil drop model (FOD), we determined that, despite their conformational diversity, all presented amyloids adopt a similar structural pattern that can be described as a ribbon-like micelle. The same model, when applied to globular proteins, results in structures referred to as "globular micelles," emerging as a result of interactions between the proteins' constituent residues and the aqueous solvent. Due to their composition, amyloids are unable to attain entropically favorable globular forms and instead attempt to limit contact between hydrophobic residues and water by producing elongated structures. Such structures typically contain quasi hydrophobic cores that stretch along the fibril's long axis. Similar properties are commonly found in ribbon-like micelles, with alternating bands of high and low hydrophobicity emerging as the fibrils increase in length. Thus, while globular proteins are generally consistent with a 3D Gaussian distribution of hydrophobicity, the distribution instead conforms to a 2D Gaussian distribution in amyloid fibrils.
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Danov KD, Kralchevsky PA, Stoyanov SD, Cook JL, Stott IP. Analytical modeling of micelle growth. 2. Molecular thermodynamics of mixed aggregates and scission energy in wormlike micelles. J Colloid Interface Sci 2019; 551:227-241. [DOI: 10.1016/j.jcis.2019.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/03/2019] [Accepted: 05/04/2019] [Indexed: 10/26/2022]
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13
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Wei Y, Gao F, Wang H, Liu G, Xia Q, Yuan S. A molecular dynamics study combining with entropy calculation on the packing state of hydrophobic chains in micelle interior. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.03.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Danov KD, Kralchevsky PA, Stoyanov SD, Cook JL, Stott IP. Analytical modeling of micelle growth. 1. Chain-conformation free energy of binary mixed spherical, wormlike and lamellar micelles. J Colloid Interface Sci 2019; 547:245-255. [PMID: 30954768 DOI: 10.1016/j.jcis.2019.03.105] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/28/2019] [Accepted: 03/30/2019] [Indexed: 11/16/2022]
Abstract
HYPOTHESES A quantitative molecular-thermodynamic theory of the growth of giant wormlike micelles of nonionic surfactants can be developed on the basis of a generalized model, which includes the classical "phase separation" and "mass action" models as special cases. The generalized model describes spherocylindrical micelles, which are simultaneously multicomponent and polydisperse in size. THEORY By analytical minimization of the free-energy functional we derived explicit expressions for the chain-extension and chain-end distribution functions in the hydrocarbon core of mixed micelles from two surfactants of different chainlengths. FINDINGS The hydrocarbon core of a two-component micelle is divided in two regions, outer and inner, where the ends of the shorter and longer chains are located. The derived analytical expression for the chain-conformation free energy implies that the mixing of surfactants with different chainlengths is always nonideal and synergistic, i.e. it leads to decrease of the micellar free energy and to enhancement of micellization and micelle growth. The derived expressions are applicable to surfactants with different headgroups (nonionic, ionic, zwitterionic) and to micelles of different shapes (spherical, wormlike, lamellar). The results can be incorporated in a quantitative theory of the growth of giant mixed micelles in formulations with practical applications in detergency.
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Affiliation(s)
- Krassimir D Danov
- Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria
| | - Peter A Kralchevsky
- Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria.
| | - Simeon D Stoyanov
- Unilever Research & Development Vlaardingen, 3133AT Vlaardingen, the Netherlands; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, 6703 HB Wageningen, the Netherlands; Department of Mechanical Engineering, University College London, WC1E 7JE, UK
| | - Joanne L Cook
- Unilever Research & Development Port Sunlight, Bebington CH63 3JW, UK
| | - Ian P Stott
- Unilever Research & Development Port Sunlight, Bebington CH63 3JW, UK
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15
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Mandal A, Gote V, Pal D, Ogundele A, Mitra AK. Ocular Pharmacokinetics of a Topical Ophthalmic Nanomicellar Solution of Cyclosporine (Cequa®) for Dry Eye Disease. Pharm Res 2019; 36:36. [DOI: 10.1007/s11095-018-2556-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/05/2018] [Indexed: 01/22/2023]
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16
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Danov KD, Kralchevsky PA, Stoyanov SD, Cook JL, Stott IP, Pelan EG. Growth of wormlike micelles in nonionic surfactant solutions: Quantitative theory vs. experiment. Adv Colloid Interface Sci 2018; 256:1-22. [PMID: 29804690 DOI: 10.1016/j.cis.2018.05.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 11/25/2022]
Abstract
Despite the considerable advances of molecular-thermodynamic theory of micelle growth, agreement between theory and experiment has been achieved only in isolated cases. A general theory that can provide self-consistent quantitative description of the growth of wormlike micelles in mixed surfactant solutions, including the experimentally observed high peaks in viscosity and aggregation number, is still missing. As a step toward the creation of such theory, here we consider the simplest system - nonionic wormlike surfactant micelles from polyoxyethylene alkyl ethers, CiEj. Our goal is to construct a molecular-thermodynamic model that is in agreement with the available experimental data. For this goal, we systematized data for the micelle mean mass aggregation number, from which the micelle growth parameter was determined at various temperatures. None of the available models can give a quantitative description of these data. We constructed a new model, which is based on theoretical expressions for the interfacial-tension, headgroup-steric and chain-conformation components of micelle free energy, along with appropriate expressions for the parameters of the model, including their temperature and curvature dependencies. Special attention was paid to the surfactant chain-conformation free energy, for which a new more general formula was derived. As a result, relatively simple theoretical expressions are obtained. All parameters that enter these expressions are known, which facilitates the theoretical modeling of micelle growth for various nonionic surfactants in excellent agreement with the experiment. The constructed model can serve as a basis that can be further upgraded to obtain quantitative description of micelle growth in more complicated systems, including binary and ternary mixtures of nonionic, ionic and zwitterionic surfactants, which determines the viscosity and stability of various formulations in personal-care and house-hold detergency.
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17
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Chen F, Yang Y, He J, Bu T, He X, He K, Xiang C, Yu Z, Wu H. The gelation of hydroxypropyl guar gum by nano-ZrO2. POLYM ADVAN TECHNOL 2017. [DOI: 10.1002/pat.4168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Fu Chen
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Yang Yang
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Jie He
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Tao Bu
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Xuemei He
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Kunyi He
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Chunlin Xiang
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Zongxue Yu
- College of Chemistry and Chemical Engineering; Southwest Petroleum University; Chengdu Sichuan 610500 China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province; Southwest Petroleum University; Chengdu Sichuan 610500 China
| | - Hongjun Wu
- Tarim Oilfield Branch Company Perto-china; Oil and Gas Engineering Institute; China
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18
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Smrt ST, Draney AW, Singaram I, Lorieau JL. Structure and Dynamics of Membrane Proteins and Membrane Associated Proteins with Native Bicelles from Eukaryotic Tissues. Biochemistry 2017; 56:5318-5327. [PMID: 28915027 DOI: 10.1021/acs.biochem.7b00575] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Sean T. Smrt
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Adrian W. Draney
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Indira Singaram
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Justin L. Lorieau
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, United States
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19
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Molugu TR, Lee S, Brown MF. Concepts and Methods of Solid-State NMR Spectroscopy Applied to Biomembranes. Chem Rev 2017; 117:12087-12132. [PMID: 28906107 DOI: 10.1021/acs.chemrev.6b00619] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Concepts of solid-state NMR spectroscopy and applications to fluid membranes are reviewed in this paper. Membrane lipids with 2H-labeled acyl chains or polar head groups are studied using 2H NMR to yield knowledge of their atomistic structures in relation to equilibrium properties. This review demonstrates the principles and applications of solid-state NMR by unifying dipolar and quadrupolar interactions and highlights the unique features offered by solid-state 2H NMR with experimental illustrations. For randomly oriented multilamellar lipids or aligned membranes, solid-state 2H NMR enables direct measurement of residual quadrupolar couplings (RQCs) due to individual C-2H-labeled segments. The distribution of RQC values gives nearly complete profiles of the segmental order parameters SCD(i) as a function of acyl segment position (i). Alternatively, one can measure residual dipolar couplings (RDCs) for natural abundance lipid samples to obtain segmental SCH order parameters. A theoretical mean-torque model provides acyl-packing profiles representing the cumulative chain extension along the normal to the aqueous interface. Equilibrium structural properties of fluid bilayers and various thermodynamic quantities can then be calculated, which describe the interactions with cholesterol, detergents, peptides, and integral membrane proteins and formation of lipid rafts. One can also obtain direct information for membrane-bound peptides or proteins by measuring RDCs using magic-angle spinning (MAS) in combination with dipolar recoupling methods. Solid-state NMR methods have been extensively applied to characterize model membranes and membrane-bound peptides and proteins, giving unique information on their conformations, orientations, and interactions in the natural liquid-crystalline state.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Soohyun Lee
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Michael F Brown
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
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20
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Murshid N, Wang X. Hydrophobic Effect of Alkyl Groups Stabilizing Self-Assembled Colloids in Water. J Phys Chem B 2017; 121:6280-6285. [DOI: 10.1021/acs.jpcb.7b04353] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nimer Murshid
- Department of Chemistry and
Waterloo Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario, N2L 3G1, Canada
| | - Xiaosong Wang
- Department of Chemistry and
Waterloo Institute for Nanotechnology, University of Waterloo, 200 University
Avenue West, Waterloo, Ontario, N2L 3G1, Canada
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21
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George SR, Champagne-Hartley R, Deeter GA, Campbell JD, Reck B, Urban D, Cunningham MF. Amphiphilic Block Copolymers as Stabilizers in Emulsion Polymerization: Effects of the Anchoring Block Molecular Weight Dispersity on Stabilization Performance. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b02111] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Sean R. George
- Department of Chemical
Engineering, Queen’s University, Kingston, ON, Canada K7L 3N6
| | | | - Gary A. Deeter
- BASF Corporation, Wyandotte, Michigan 48192, United States
| | - J. D. Campbell
- BASF Corporation, Wyandotte, Michigan 48192, United States
| | | | | | - Michael F. Cunningham
- Department of Chemical
Engineering, Queen’s University, Kingston, ON, Canada K7L 3N6
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22
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Abstract
Although computer simulation of biological molecules has seen widespread growth and is widely accepted as an important biochemical tool, it is hampered by lim ited computing resources. Biomolecular systems, by necessity, contain a large number of interaction sites. In many cases, these sites interact over quite large dis tances. Further, the time scales of biological interest are long, which requires that simulations of dynamical properties at the atomic level must be lengthy to ade quately probe these motions. We address these issues through discussions of atomic-level molecular dynam ics simulations of biological lipid bilayer membranes, which are key constructs in biochemistry. These simu lations reproduce many experimental observables and provide a degree of resolution currently unavailable experimentally. The lengths of these simulations, the longest of which was 2 nanoseconds, were sufficient to effectively sample many of the motions governing the behavior of biomembranes. Examples are given showing the importance of long-range interactions. The number of interaction sites required by these sim ulations is discussed, particularly the need for explicit representation of solvent molecules.
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Affiliation(s)
- Terry R. Stouch
- BRISTOL-MYERS SQUIBB PHARMACEUTICAL RESEARCH INSTITUTE P.O. BOX 4000 PRINCETON, NJ 08543-4000
| | - Howard E. Alper
- BRISTOL-MYERS SQUIBB PHARMACEUTICAL RESEARCH INSTITUTE P.O. BOX 4000 PRINCETON, NJ 08543-4000
| | - Donna Bassolino-Klimas
- BRISTOL-MYERS SQUIBB PHARMACEUTICAL RESEARCH INSTITUTE P.O. BOX 4000 PRINCETON, NJ 08543-4000
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23
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Lindman B. From surfactant to cellulose and DNA self-assembly. A 50-year journey. Colloid Polym Sci 2016; 294:1687-1703. [PMID: 27795609 PMCID: PMC5063899 DOI: 10.1007/s00396-016-3927-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/07/2016] [Accepted: 07/30/2016] [Indexed: 11/06/2022]
Abstract
Surfactants have been the basis for applications in several industrial sectors for a long time. However, fundamental research was 50 years ago still limited to a small number of academic groups and even basic aspects were controversial. The field has since undergone an enormous expansion and the improved understanding has laid the basis of numerous new products as well as been the basis of important parts of nano-science and -technology.The present author has during 50 years in academia devoted most of his research to amphiphilic compounds, including both surfactants and polymers. Hereby, I had the privilege of following a very exciting development. In 2015, I had the honour to receive the Life-time Achievement Award of IACIS, the International Association of Colloid and Interface Scientists. IACIS organizes since the 1970s a tri-annual symposium, typically the best attended in the field. For the first time since 2000, it was in 2015 organized in Europe, namely Mainz, Germany. This treatise is based on my award lecture in Mainz, which covered developments from my first research as a new Ph D student in Stockholm to current work as an emeritus and visiting professor. Interestingly, discoveries in my very early work contributed to solving problems in now on-going research. Håkan Wennerström kindly wrote a quite comprehensive paper about my achievements a few years ago (Adv Colloid Interf Sci 205:1-8, [1]). In writing the present paper, I have strived at covering mainly topics not treated in detail by Håkan. In fact, I will emphasize very much our early studies as well as our studies of surfactant self-assembly by NMR and in particular look at the developments of our research and connections between different research topics.
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Affiliation(s)
- Björn Lindman
- Physical Chemistry, University of Lund, P.O. Box 124, 221 00 Lund, Sweden
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24
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Mobasheri M, Attar H, Rezayat Sorkhabadi SM, Khamesipour A, Jaafari MR. Solubilization Behavior of Polyene Antibiotics in Nanomicellar System: Insights from Molecular Dynamics Simulation of the Amphotericin B and Nystatin Interactions with Polysorbate 80. Molecules 2015; 21:E6. [PMID: 26712721 PMCID: PMC6273564 DOI: 10.3390/molecules21010006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/26/2015] [Accepted: 11/27/2015] [Indexed: 01/23/2023] Open
Abstract
Amphotericin B (AmB) and Nystatin (Nys) are the drugs of choice for treatment of systemic and superficial mycotic infections, respectively, with their full clinical potential unrealized due to the lack of high therapeutic index formulations for their solubilized delivery. In the present study, using a coarse-grained (CG) molecular dynamics (MD) simulation approach, we investigated the interaction of AmB and Nys with Polysorbate 80 (P80) to gain insight into the behavior of these polyene antibiotics (PAs) in nanomicellar solution and derive potential implications for their formulation development. While the encapsulation process was predominantly governed by hydrophobic forces, the dynamics, hydration, localization, orientation, and solvation of PAs in the micelle were largely controlled by hydrophilic interactions. Simulation results rationalized the experimentally observed capability of P80 in solubilizing PAs by indicating (i) the dominant kinetics of drugs encapsulation over self-association; (ii) significantly lower hydration of the drugs at encapsulated state compared with aggregated state; (iii) monomeric solubilization of the drugs; (iv) contribution of drug-micelle interactions to the solubilization; (v) suppressed diffusivity of the encapsulated drugs; (vi) high loading capacity of the micelle; and (vii) the structural robustness of the micelle against drug loading. Supported from the experimental data, our simulations determined the preferred location of PAs to be the core-shell interface at the relatively shallow depth of 75% of micelle radius. Deeper penetration of PAs was impeded by the synergistic effects of (i) limited diffusion of water; and (ii) perpendicular orientation of these drug molecules with respect to the micelle radius. PAs were solvated almost exclusively in the aqueous poly-oxyethylene (POE) medium due to the distance-related lack of interaction with the core, explaining the documented insensitivity of Nys solubilization to drug-core compatibility in detergent micelles. Based on the obtained results, the dearth of water at interior sites of micelle and the large lateral occupation space of PAs lead to shallow insertion, broad radial distribution, and lack of core interactions of the amphiphilic drugs. Hence, controlled promotion of micelle permeability and optimization of chain crowding in palisade layer may help to achieve more efficient solubilization of the PAs.
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Affiliation(s)
- Meysam Mobasheri
- Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran 1477893855, Iran.
| | - Hossein Attar
- Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran 1477893855, Iran.
- Tofigh Daru Research and Engineering Company (TODACO), Tehran 1397116359, Iran.
| | - Seyed Mehdi Rezayat Sorkhabadi
- Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran 1417755469, Iran.
- Department of Toxicology and Pharmacology, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran 193956466, Iran.
| | - Ali Khamesipour
- Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, Tehran 1416613675, Iran.
| | - Mahmoud Reza Jaafari
- Biotechnology Research Center, Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, P. O. Box: 91775-1365, Mashhad 917751365, Iran.
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25
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George S, Champagne-Hartley R, Deeter G, Campbell D, Reck B, Urban D, Cunningham M. Amphiphilic Block Copolymers as Stabilizers in Emulsion Polymerization: Effects of the Stabilizing Block Molecular Weight Dispersity on Stabilization Performance. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01853] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sean George
- Department
of Chemical Engineering, Queen’s University, Kingston, ON, Canada K7L 3N6
| | | | - Gary Deeter
- BASF Corporation, Wyandotte, Michigan 48192, United States
| | - Dave Campbell
- BASF Corporation, Wyandotte, Michigan 48192, United States
| | | | | | - Michael Cunningham
- Department
of Chemical Engineering, Queen’s University, Kingston, ON, Canada K7L 3N6
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26
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Affiliation(s)
- Joshua A. Long
- Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Blake M. Rankin
- Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dor Ben-Amotz
- Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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27
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Leftin A, Molugu TR, Job C, Beyer K, Brown MF. Area per lipid and cholesterol interactions in membranes from separated local-field (13)C NMR spectroscopy. Biophys J 2015; 107:2274-86. [PMID: 25418296 DOI: 10.1016/j.bpj.2014.07.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/24/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state (13)C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved (13)C-(1)H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the (13)C-(1)H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state (13)C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive.
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Affiliation(s)
- Avigdor Leftin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Constantin Job
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Klaus Beyer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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28
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Tej Varma Y, Joshi S, Pant DD. Effect of nanosize micelles of ionic and neutral surfactants on the photophysics of protonated 6-methoxyquinoline: time-resolved fluorescence study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 138:818-826. [PMID: 25434640 DOI: 10.1016/j.saa.2014.10.118] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/24/2014] [Accepted: 10/26/2014] [Indexed: 06/04/2023]
Abstract
The excited state dynamic studies have been carried out to investigate the effects of micellar surface charge on the photophysics of protonated 6-methoxyquinoline (6MQ(+)) in anionic, sodium dodecylsulphate (SDS), cationic, cetyltrimethylammonium bromide (CTAB) and neutral, triton X-100 (TX100) surfactant at premicellar, micellar and postmicellar concentrations in aqueous phase at room temperature. At premicellar concentrations of SDS, there is a slight decrease in emission intensity and at micellar and postmicellar concentrations, increase in emission intensity and blue shift of spectrum has been observed. The blue shift in fluorescence spectrum and slight increase in quantum yield are attributed to incorporation of solute molecule to the micelles. Edge excitation red shift (EERS) in fluorescence maximum of 6MQ(+) has been observed in all the surfactant solutions studied. The EERS has been ascribed in terms of solvent relaxation process. In SDS surfactant system, due to heterogeneous restricted motion of solvent molecules, the solvent viscosity increases which results in an increase in net magnitude of EERS. The fluorescence decay components of 6MQ(+) fit with multi exponential functions in all the micellar systems studied. The location of the probe molecule in micellar systems is justified by a variety of spectral parameters such as refractive index, dielectric constant, ET (30), EERS, average fluorescence decay time, radiative and non radiative rate constants, and rotational relaxation time.
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Affiliation(s)
- Y Tej Varma
- Department of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Sunita Joshi
- Department of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India
| | - Debi D Pant
- Department of Physics, Birla Institute of Technology and Science (BITS) Pilani, Pilani 333031, Rajasthan, India.
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29
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30
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Monduzzi M, Lampis S, Murgia S, Salis A. From self-assembly fundamental knowledge to nanomedicine developments. Adv Colloid Interface Sci 2014; 205:48-67. [PMID: 24182715 DOI: 10.1016/j.cis.2013.10.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/08/2013] [Accepted: 10/08/2013] [Indexed: 02/01/2023]
Abstract
This review highlights the key role of NMR techniques in demonstrating the molecular aspects of the self-assembly of surfactant molecules that nowadays constitute the basic knowledge which modern nanoscience relies on. The aim is to provide a tutorial overview. The story of a rigorous scientific approach to understand self-assembly in surfactant systems and biological membranes starts in the early seventies when the progresses of SAXRD and NMR technological facilities allowed to demonstrate the existence of ordered soft matter, and the validity of Tanford approach concerning self-assembly at a molecular level. Particularly, NMR quadrupolar splittings, NMR chemical shift anisotropy, and NMR relaxation of dipolar and quadrupolar nuclei in micellar solutions, microemulsions, and liquid crystals proved the existence of an ordered polar-apolar interface, on the NMR time scale. NMR data, rationalized in terms of the two-step model of relaxation, allowed to quantify the dynamic aspects of the supramolecular aggregates in different soft matter systems. In addition, NMR techniques allowed to obtain important information on counterion binding as well as on size of the aggregate through molecular self-diffusion. Indeed NMR self-diffusion proved without any doubt the existence of bicontinuous microemulsions and bicontinuous cubic liquid crystals, suggested by pioneering and brilliant interpretation of SAXRD investigations. Moreover, NMR self-diffusion played a fundamental role in the understanding of microemulsion and emulsion nanostructures, phase transitions in phase diagrams, and particularly percolation phenomena in microemulsions. Since the nineties, globalization of the knowledge along with many other technical facilities such as electron microscopy, particularly cryo-EM, produced huge progresses in surfactant and colloid science. Actually we refer to nanoscience: bottom up/top down strategies allow to build nanodevices with applications spanning from ICT to food technology. Developments in the applied fields have also been addressed by important progresses in theoretical skills aimed to understand intermolecular forces, and specific ion interactions. Nevertheless, this is still an open question. Our predictive ability has however increased, hence more ambitious targets can be planned. Nanomedicine represents a major challenging field with its main aims: targeted drug delivery, diagnostic, theranostics, tissue engineering, and personalized medicine. Few recent examples will be mentioned. Although the real applications of these systems still need major work, nevertheless new challenges are open, and perspectives based on integrated multidisciplinary approaches would enable both a deeper basic knowledge and the expected advances in biomedical field.
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Affiliation(s)
- Maura Monduzzi
- Dept. Scienze Chimiche e Geologiche, CNBS & CSGI, University of Cagliari, SS 554 Bivio Sestu, 09042 Monserrato, CA, Italy.
| | - Sandrina Lampis
- Dept. Scienze Chimiche e Geologiche, CNBS & CSGI, University of Cagliari, SS 554 Bivio Sestu, 09042 Monserrato, CA, Italy
| | - Sergio Murgia
- Dept. Scienze Chimiche e Geologiche, CNBS & CSGI, University of Cagliari, SS 554 Bivio Sestu, 09042 Monserrato, CA, Italy
| | - Andrea Salis
- Dept. Scienze Chimiche e Geologiche, CNBS & CSGI, University of Cagliari, SS 554 Bivio Sestu, 09042 Monserrato, CA, Italy
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31
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Oliver RC, Lipfert J, Fox DA, Lo RH, Doniach S, Columbus L. Dependence of micelle size and shape on detergent alkyl chain length and head group. PLoS One 2013; 8:e62488. [PMID: 23667481 PMCID: PMC3648574 DOI: 10.1371/journal.pone.0062488] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/20/2013] [Indexed: 11/19/2022] Open
Abstract
Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC) currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS), micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2-1.5 Å per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ∼16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.
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Affiliation(s)
- Ryan C. Oliver
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, United States of America
| | - Jan Lipfert
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Daniel A. Fox
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, United States of America
| | - Ryan H. Lo
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, United States of America
| | - Sebastian Doniach
- Departments of Physics and Applied Physics, Biophysics Program, Stanford, California, United States of America
- Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California, United States of America
| | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, United States of America
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32
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Abstract
Abstract
Nonionic surfactants do not produce ions in aqueous solution. As a consequence, they are compatible with other types of surfactants and are excellent candidates to enter complex mixtures, as found in many commercial products. Nonionic surfactants are found today in a large variety of domestic and industrial products, such as powdered or liquid formulations. This review paper describes the history, properties, types and uses of nonionic surfactants.
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33
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Khorwal V, Datta A. Ground and excited state prototropism of 2-(4′-pyridyl)benzimidazole in micelles. J Photochem Photobiol A Chem 2012. [DOI: 10.1016/j.jphotochem.2012.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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34
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Profile of Ken A. Dill. Proc Natl Acad Sci U S A 2012; 109:3194-6. [PMID: 22315429 DOI: 10.1073/pnas.1200576109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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35
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Al-Abdul-Wahid MS, Evanics F, Prosser RS. Dioxygen transmembrane distributions and partitioning thermodynamics in lipid bilayers and micelles. Biochemistry 2011; 50:3975-83. [PMID: 21510612 DOI: 10.1021/bi200168n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cellular respiration, mediated by the passive diffusion of oxygen across lipid membranes, is key to many basic cellular processes. In this work, we report the detailed distribution of oxygen across lipid bilayers and examine the thermodynamics of oxygen partitioning via NMR studies of lipids in a small unilamellar vesicle (SUV) morphology. Dissolved oxygen gives rise to paramagnetic chemical shift perturbations and relaxation rate enhancements, both of which report on local oxygen concentration. From SUVs containing the phospholipid sn-2-perdeuterio-1-myristelaidoyl, 2-myristoyl-sn-glycero-3-phosphocholine (MLMPC), an analogue of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), we deduced the complete trans-bilayer oxygen distribution by measuring (13)C paramagnetic chemical shifts perturbations for 18 different sites on MLMPC arising from oxygen at a partial pressure of 30 bar. The overall oxygen solubility at 45 °C spans a factor of 7 between the bulk water (23.7 mM) and the bilayer center (170 mM) and is lowest in the vicinity of the phosphocholine headgroup, suggesting that oxygen diffusion across the glycerol backbone should be the rate-limiting step in diffusion-mediated passive transport of oxygen across the lipid bilayer. Lowering of the temperature from 45 to 25 °C gave rise to a slight decrease of the oxygen solubility within the hydrocarbon interior of the membrane. An analysis of the temperature dependence of the oxygen solubility profile, as measured by (1)H paramagnetic relaxation rate enhancements, reveals that oxygen partitioning into the bilayer is entropically favored (ΔS° = 54 ± 3 J K(-1) mol(-1)) and must overcome an enthalpic barrier (ΔH° = 12.0 ± 0.9 kJ mol(-1)).
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Affiliation(s)
- M Sameer Al-Abdul-Wahid
- Department of Chemistry, University of Toronto, UTM, North Mississauga, Ontario, Canada L5L 1C6
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Hovers J, Potschies M, Polidori A, Pucci B, Raynal S, Bonneté F, Serrano-Vega MJ, Tate CG, Picot D, Pierre Y, Popot JL, Nehmé R, Bidet M, Mus-Veteau I, Busskamp H, Jung KH, Marx A, Timmins PA, Welte W. A class of mild surfactants that keep integral membrane proteins water-soluble for functional studies and crystallization. Mol Membr Biol 2011; 28:171-81. [PMID: 21314479 DOI: 10.3109/09687688.2011.552440] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mixed protein-surfactant micelles are used for in vitro studies and 3D crystallization when solutions of pure, monodisperse integral membrane proteins are required. However, many membrane proteins undergo inactivation when transferred from the biomembrane into micelles of conventional surfactants with alkyl chains as hydrophobic moieties. Here we describe the development of surfactants with rigid, saturated or aromatic hydrocarbon groups as hydrophobic parts. Their stabilizing properties are demonstrated with three different integral membrane proteins. The temperature at which 50% of the binding sites for specific ligands are lost is used as a measure of stability and dodecyl-β-D-maltoside ('C12-b-M') as a reference for conventional surfactants. One surfactant increased the stability of two different G protein-coupled receptors and the human Patched protein receptor by approximately 10°C compared to C12-b-M. Another surfactant yielded the highest stabilization of the human Patched protein receptor compared to C12-b-M (13°C) but was inferior for the G protein-coupled receptors. In addition, one of the surfactants was successfully used to stabilize and crystallize the cytochrome b(6 )f complex from Chlamydomonas reinhardtii. The structure was solved to the same resolution as previously reported in C12-b-M.
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Affiliation(s)
- Jens Hovers
- Fachbereich Biologie, Universität Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany
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37
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Sammalkorpi M, Sanders S, Panagiotopoulos AZ, Karttunen M, Haataja M. Simulations of Micellization of Sodium Hexyl Sulfate. J Phys Chem B 2011; 115:1403-10. [DOI: 10.1021/jp109882r] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- M. Sammalkorpi
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States, and Department of Chemistry, Aalto University School of Chemical Technology, Helsinki, Finland
| | - S. Sanders
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States
| | - A. Z. Panagiotopoulos
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States
| | - M. Karttunen
- Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada
| | - M. Haataja
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, United States
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38
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Gogonea V, Wu Z, Lee X, Pipich V, Li XM, Ioffe AI, Didonato JA, Hazen SL. Congruency between biophysical data from multiple platforms and molecular dynamics simulation of the double-super helix model of nascent high-density lipoprotein. Biochemistry 2010; 49:7323-43. [PMID: 20687589 DOI: 10.1021/bi100588a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The predicted structure and molecular trajectories from >80 ns molecular dynamics simulation of the solvated Double-Super Helix (DSH) model of nascent high-density lipoprotein (HDL) were determined and compared with experimental data on reconstituted nascent HDL obtained from multiple biophysical platforms, including small angle neutron scattering (SANS) with contrast variation, hydrogen-deuterium exchange tandem mass spectrometry (H/D-MS/MS), nuclear magnetic resonance spectroscopy (NMR), cross-linking tandem mass spectrometry (MS/MS), fluorescence resonance energy transfer (FRET), electron spin resonance spectroscopy (ESR), and electron microscopy. In general, biophysical constraints experimentally derived from the multiple platforms agree with the same quantities evaluated using the simulation trajectory. Notably, key structural features postulated for the recent DSH model of nascent HDL are retained during the simulation, including (1) the superhelical conformation of the antiparallel apolipoprotein A1 (apoA1) chains, (2) the lipid micellar-pseudolamellar organization, and (3) the solvent-exposed Solar Flare loops, proposed sites of interaction with LCAT (lecithin cholesteryl acyltransferase). Analysis of salt bridge persistence during simulation provides insights into structural features of apoA1 that forms the backbone of the lipoprotein. The combination of molecular dynamics simulation and experimental data from a broad range of biophysical platforms serves as a powerful approach to studying large macromolecular assemblies such as lipoproteins. This application to nascent HDL validates the DSH model proposed earlier and suggests new structural details of nascent HDL.
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Affiliation(s)
- Valentin Gogonea
- Department of Chemistry, Cleveland State University, Cleveland, Ohio 44115, USA.
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40
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Nusselder JJH, Engberts JBFN, Boelens R, Kaptein R. Micellar structure studied by 2D-NMR. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19881070210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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41
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42
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Ben-Shaul A, Szleifer I, Gelbart WM. Statistical thermodynamics of amphiphile chains in micelles. Proc Natl Acad Sci U S A 2010; 81:4601-5. [PMID: 16593492 PMCID: PMC345641 DOI: 10.1073/pnas.81.14.4601] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The probability distribution of amphiphile chain conformations in micelles of different geometries is derived through maximization of their packing entropy. A lattice model, first suggested by Dill and Flory, is used to represent the possible chain conformations in the micellar core. The polar heads of the chains are assumed to be anchored to the micellar surface, with the other chain segments occupying all lattice sites in the interior of the micelle. This "volume-filling" requirement, the connectivity of the chains, and the geometry of the micelle define constraints on the possible probability distributions of chain conformations. The actual distribution is derived by maximizing the chain's entropy subject to these constraints; "reversals" of the chains back towards the micellar surface are explicitly included. Results are presented for amphiphiles organized in planar bilayers and in cylindrical and spherical micelles of different sizes. It is found that, for all three geometries, the bond order parameters decrease as a function of the bond distance from the polar head, in accordance with recent experimental data. The entropy differences associated with geometrical changes are shown to be significant, suggesting thereby the need to include curvature (environmental)-dependent "tail" contributions in statistical thermodynamic treatments of micellization.
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Affiliation(s)
- A Ben-Shaul
- Department of Physical Chemistry and The Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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43
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Fromherz P. The Surfactant-Block Structure of Micelles, Synthesis of the Droplet and of the Bilayer Concept. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19810851015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Smith AM, Vinchurkar M, Gronbech-Jensen N, Parikh AN. Order at the Edge of the Bilayer: Membrane Remodeling at the Edge of a Planar Supported Bilayer Is Accompanied by a Localized Phase Change. J Am Chem Soc 2010; 132:9320-7. [DOI: 10.1021/ja100294k] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andreia M. Smith
- Biophysics Graduate Group, University of California, Davis, California 95616, and Department of Applied Science, University of California, Davis, California 95616
| | - Madhuri Vinchurkar
- Biophysics Graduate Group, University of California, Davis, California 95616, and Department of Applied Science, University of California, Davis, California 95616
| | - Niels Gronbech-Jensen
- Biophysics Graduate Group, University of California, Davis, California 95616, and Department of Applied Science, University of California, Davis, California 95616
| | - Atul N. Parikh
- Biophysics Graduate Group, University of California, Davis, California 95616, and Department of Applied Science, University of California, Davis, California 95616
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Kalus J, Hoffmann H, Reizlein K, Ulbricht W, Ibel K. Small Angle Neutron Scattering Measurements on Ionic Detergent Solutions with Rodlike Micelles. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19820860108] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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47
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Vijay R, Singh J, Baskar G, Ranganathan R. Amphiphilic lauryl ester derivatives from aromatic amino acids: significance of chemical architecture in aqueous aggregation properties. J Phys Chem B 2010; 113:13959-70. [PMID: 19778004 DOI: 10.1021/jp905384y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lauryl esters of L-tyrosine (LET) and L-phenylalanine (LEP) were, in a previous interface adsorption study, found to adopt very different interfacial conformations. The present study is an investigation of their aqueous aggregation properties with the goal of elucidating the effects of the presence in LET and absence in LEP of the phenolic OH group on their aqueous aggregate structures and micellar conformations of the surfactant monomers. The measured properties included aggregation numbers from time-resolved fluorescence quenching (TRFQ), interface hydration index and microviscosity by electron spin resonance (ESR), chemical shifts of (1)H resonance lines by NMR, and Krafft temperatures and enthalpies of structural transitions by differential scanning calorimetry (DSC). The TRFQ, ESR, and NMR experiments were conducted at various temperatures from 23 to 70 degrees C for various surfactant concentrations from 0.050 to 0.200 M. Markedly different temperature dependences of aggregation number and (1)H NMR chemical shifts are exhibited by LET and LEP micelles. LET and LEP form ionic micelles. The aggregation number of LEP decreases as is characteristic of ionic micelles, but that of LET increases slightly with temperature. The changes with temperature in the NMR chemical shifts and width of the resonance lines are significantly greater for the various LEP protons than for those of LET. The differences in these properties and other fluorescence decay characteristics of fluorophores incorporated into the micelles could be attributed to the difference in the micellar conformations of LET and LEP which are postulated to be similar to that at oil-water interfaces. The phenolic group is hypothesized to be in the micelle-water interface as part of the headgroup in LET micelles, and its location does not change with temperature. On the other hand, in LEP micelles, the phenyl ring is folded into the core overlapping with the flexible hydrophobic chains. The resulting closer proximity between the phenyl ring and the flexible hydrocarbon chain causes interdependence of the phenyl ring and chain proton resonances, leading to the observed temperature dependence of the chemical shifts in LEP. The TRFQ and ESR data are combined together in a molecular space-filling model, referred to as the polar shell model, to derive the geometrical properties of the micelle. The DSC scans in the temperature range 10-55 degrees C showed the presence of distinctly different endotherms for LET and LEP. The Krafft temperatures, K(T), and the enthalpies were determined. The higher K(T) and broader peak of the DSC endotherm of LET as compared to LEP are attributed to the stabilization of fiberlike structures below the Krafft temperature due to its chirality and the hydrogen bonding capability of the phenolic OH and also to the ion-dipole interactions. Thus, all of the observed differences between LET and LEP could be attributed to the difference in their chemical architecture.
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Affiliation(s)
- R Vijay
- Industrial Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
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BANDYOPADHYAY SANJOY, KLEIN MICHAELL, MARTYNA GLENNJ, TAREK MOUNIR. Molecular dynamics studies of the hexagonal mesophase of sodium dodecylsulphate in aqueous solution. Mol Phys 2009. [DOI: 10.1080/00268979809483170] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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49
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Sammalkorpi M, Karttunen M, Haataja M. Ionic Surfactant Aggregates in Saline Solutions: Sodium Dodecyl Sulfate (SDS) in the Presence of Excess Sodium Chloride (NaCl) or Calcium Chloride (CaCl2). J Phys Chem B 2009; 113:5863-70. [DOI: 10.1021/jp901228v] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Sammalkorpi
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, and Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Mikko Karttunen
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, and Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Mikko Haataja
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, and Department of Applied Mathematics, The University of Western Ontario, London, Ontario, Canada N6A 5B7
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50
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Misra PK, Somasundaran P. Fluorescence Probing of the Surfactant Assemblies in Solutions and at Solid–Liquid Interfaces. ADVANCES IN POLYMER SCIENCE 2008. [DOI: 10.1007/12_2008_165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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