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Pem B, Pišonić M, Momčilov M, Crnolatac I, Brkljača Z, Vazdar M, Bakarić D. Protonation of palmitic acid embedded in DPPC lipid bilayers obscures detection of ripple phase by FTIR spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 322:124773. [PMID: 39002469 DOI: 10.1016/j.saa.2024.124773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/03/2024] [Accepted: 07/02/2024] [Indexed: 07/15/2024]
Abstract
The transformation of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid bilayers from the gel (Lβ') to the fluid (Lα) phase involves an intermediate ripple (Pβ') phase forming a few degrees below the main transition temperature (Tm). While the exact cause of bilayer rippling is still debated, the presence of amphiphilic molecules, pH, and lipid bilayer architecture are all known to influence (pre)transition behavior. In particular, fatty acid chains interact with hydrophobic lipid tails, while the carboxylic groups simultaneously participate in proton transfer with interfacial water in the polar lipid region which is controlled by the pH of the surrounding aqueous medium. The molecular-level variations in the DPPC ripple phase in the presence of 2% palmitic acid (PA) were studied at pH levels 4.0, 7.3, and 9.1, where PA is fully protonated, partially protonated, or fully deprotonated. Bilayer thermotropic behavior was investigated by differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR) spectroscopy which agreed in their characterization of (pre)transition at pH of 9.1, but not at pH 4.0 and especially not at 7.3. Owing to the different insertion depths of protonated and deprotonated PA, along with the ability of protonated PA to undergo flip-flop in the bilayer, these two forms of PA show a different hydration pattern in the interfacial water layer. Finally, these results demonstrated the hitherto undiscovered potential of FTIR spectroscopy in the detection of the events occurring at the surface of lipid bilayers that obscure the low-cooperativity phase transition explored in this work.
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Affiliation(s)
- Barbara Pem
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Marina Pišonić
- Division of Analytical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia
| | - Marina Momčilov
- Division of Analytical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia
| | - Ivo Crnolatac
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Zlatko Brkljača
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Mario Vazdar
- Department of Mathematics, Informatics, and Cybernetics, University of Chemistry and Technology, Technická 5, 16628 Prague, Czech Republic
| | - Danijela Bakarić
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
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2
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Nagle JF. Understanding the phase behavior of a protobiomembrane. Phys Rev E 2023; 107:064408. [PMID: 37464660 DOI: 10.1103/physreve.107.064408] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 06/13/2023] [Indexed: 07/20/2023]
Abstract
The rich thermotropic behavior of lipid bilayers is addressed using phenomenological theory informed by many experiments. The most recent experiment not yet addressed by theory has shown that the tilt modulus in DMPC lipid bilayers decreases dramatically as the temperature is lowered toward the main transition temperature T_{M}. It is shown that this behavior can be understood by introducing a simple free energy functional for tilt that couples to the area per molecule. This is combined with a chain melting free energy functional in which the area is the primary order parameter that is the driver of the main transition. Satisfactory agreement with experiment is achieved with values of the model parameters determined by experiments, but the transition is directly into the gel phase. The theory is then extended to include the enigmatic ripple phase by making contact with the most recent experimentally determined ripple structure.
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Affiliation(s)
- John F Nagle
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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3
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Rathod AK, Chavda D, Manna M. Phase Transition and Phase Separation in Realistic Thylakoid Lipid Membrane of Marine Algae in All-Atom Simulations. J Chem Inf Model 2023. [PMID: 37075469 DOI: 10.1021/acs.jcim.2c01614] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Thylakoid membranes are specialized membranes predominantly composed of uncommon galacto- and sulfolipids, having distinct roles in photosynthesis. Large acyl chain variety and richness in polyunsaturated fatty acid (PUFA) content of thylakoid lipids further add to the compositional complexity. The function of these membrane systems is intimately dependent on the fluidity of its lipid matrix, which is strongly modulated by the lipid composition and temperature. The present work, employing extensive atomistic simulations, provides the first atomistic view of the phase transition and domain coexistence in a model membrane composed of thylakoid lipids of a commercially important red alga Gracilaria corticata between 10 and 40 °C. The growth and photosynthetic activity of marine algae are greatly influenced by the seawater temperature. So far, little is known about the molecular organization of lipids in thylakoid membranes, in particular their adaptive arrangements under temperature stress. Our simulations show that the algal thylakoid membrane undergoes a transition from a gel-like phase at a low temperature, 10-15 °C, to a homogeneous liquid-crystalline phase at a high temperature, 40 °C. Clear evidence of spontaneous phase separation into coexisting nanoscale domains is detected at intermediate temperatures nearing the optimal growth temperature range. Particularly, at 25-30 °C, we identified the formation of a stable ripple phase, where the gel-like domains rich in saturated and nearly hexagonally packed lipids were separated from fluid-like domains enriched in lipids containing PUFA chains. The phase separation is driven by the spontaneous and preferential segregation of lipids into differentially ordered domains, mainly depending on the acyl chain types. Cholesterol impairs the phase transition and the emergence of domains and induces a fairly uniform liquid-ordered phase in the membrane over the temperatures studied. This work improves the understanding of the properties and reorganization of lipids in the thylakoid membrane in response to temperature variation.
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Affiliation(s)
- Arun K Rathod
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Dhruvil Chavda
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Moutusi Manna
- Applied Phycology and Biotechnology Division, CSIR Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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4
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Roux M, Legrand FX, Bil A, Bonnet V, Djedaini-Pilard F. Fragmentation of DMPC Membranes by a Wedge-Shaped Amphiphilic Cyclodextrin into Bicellar-like Aggregates. J Phys Chem B 2023; 127:2475-2487. [PMID: 36913407 DOI: 10.1021/acs.jpcb.2c07331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Small bilayer lipid aggregates such as bicelles provide useful isotropic or anisotropic membrane mimetics for structural studies of biological membranes. We have shown previously by deuterium NMR that a wedge-shaped amphiphilic derivative of trimethyl βcyclodextrin anchored in deuterated DMPC-d27 bilayers through a lauryl acyl chain (TrimβMLC) is able to induce magnetic orientation and fragmentation of the multilamellar membranes. The fragmentation process fully detailed in the present paper is observed with 20% cyclodextrin derivative below 37 °C, where pure TrimβMLC self-assembles in water into large giant micellar structures. After deconvolution of a broad composite 2H NMR isotropic component, we propose a model where the DMPC membranes are progressively disrupted by TrimβMLC into small and large micellar aggregates depending whether they are extracted from the outer or inner layers of the liposomes. Below the fluid-to-gel transition of pure DMPC-d27 membranes (Tc = 21.5 °C), the micellar aggregates vanish progressively until complete extinction at 13 °C, with a probable release of pure TrimβMLC micelles leaving lipid bilayers in the gel phase doped with only a small amount of the cyclodextrin derivative. Bilayer fragmentation between Tc and 13 °C was also observed with 10% and 5% of TrimβMLC, with NMR spectra suggesting possible interactions of micellar aggregates with fluid-like lipids of the Pβ' ripple phase. No membrane orientation and fragmentation was detected with unsaturated POPC membranes, which are able to accommodate the insertion of TrimβMLC without important perturbation. The data are discussed in relation to the formation of possible DMPC bicellar aggregates such as those known to occur after insertion of dihexanoylphosphatidylcholine (DHPC). These bicelles are in particular associated with similar deuterium NMR spectra exhibiting identical composite isotropic components which were never characterized before.
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Affiliation(s)
- Michel Roux
- Université Paris-Saclay, Institute for Integrative Biology of the Cell, URA CNRS 9198, F-91191 Gif sur Yvette CEDEX, France
| | | | - Abed Bil
- Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources, (CNRS UMR 7378), Université de Picardie Jules Verne, 33 Rue Saint Leu, F-80039 Amiens, France
| | - Véronique Bonnet
- Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources, (CNRS UMR 7378), Université de Picardie Jules Verne, 33 Rue Saint Leu, F-80039 Amiens, France
| | - Florence Djedaini-Pilard
- Laboratoire de Glycochimie, des Antimicrobiens et des Agroressources, (CNRS UMR 7378), Université de Picardie Jules Verne, 33 Rue Saint Leu, F-80039 Amiens, France
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Davies M, Reyes-Figueroa AD, Gurtovenko AA, Frankel D, Karttunen M. Elucidating lipid conformations in the ripple phase: Machine learning reveals four lipid populations. Biophys J 2023; 122:442-450. [PMID: 36403088 PMCID: PMC9892614 DOI: 10.1016/j.bpj.2022.11.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 06/28/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
A new mixed radial-angular, three-particle correlation function method in combination with unsupervised machine learning was applied to examine the emergence of the ripple phase in dipalmitoylphosphatidylcholine (DPPC) lipid bilayers using data from atomistic molecular dynamics simulations of system sizes ranging from 128 to 4096 lipids. Based on the acyl tail conformations, the analysis revealed the presence of four distinct conformational populations of lipids in the ripple phases of the DPPC lipid bilayers. The expected gel-like (ordered; Lo) and fluid-like (disordered; Ld) lipids are found along with their splayed tail equivalents (Lo,s and Ld,s). These lipids differ, based on their gauche distribution and tail packing. The disordered (Ld) and disordered-splayed (Ld,s) lipids spatially cluster in the ripple in the groove side, that is, in an asymmetric manner across the bilayer leaflets. The ripple phase does not contain large numbers of Ld lipids; instead they only exist on the interface of the groove side of the undulation. The bulk of the groove side is a complex coexistence of Lo,Lo,s, and Ld,s lipids. The convex side of the undulation contains predominantly Lo lipids. Thus, the structure of the ripple phase is neither a simple coexistence of ordered and disordered lipids nor a coexistence of ordered interdigitating gel-like (Lo) and ordered-splayed (Lo,s) lipids, but instead a coexistence of an ordered phase and a complex mixed phase. Principal component analysis further confirmed the existence of the four lipid groups.
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Affiliation(s)
- Matthew Davies
- School of Engineering, Newcastle University, Newcastle, United Kingdom
| | - A D Reyes-Figueroa
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada; The Centre of Advanced Materials and Biomaterials Research, The University of Western Ontario, London, Ontario, Canada; Centro de Investigación en Matemáticas Unidad Monterrey, Apodaca, Nuevo León, México; Consejo Nacional de Ciencia y Tecnología, Benito Juárez, Ciudad de México, Mexico
| | - Andrey A Gurtovenko
- Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia; Faculty of Physics, St. Petersburg State University, St. Petersburg, Russia
| | - Daniel Frankel
- School of Engineering, Newcastle University, Newcastle, United Kingdom
| | - Mikko Karttunen
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada; The Centre of Advanced Materials and Biomaterials Research, The University of Western Ontario, London, Ontario, Canada; Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, Canada.
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6
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Maleš P, Butumović M, Erceg I, Brkljača Z, Bakarić D. Influence of DPPE surface undulations on melting temperature determination: UV/Vis spectroscopic and MD study. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184072. [PMID: 36216096 DOI: 10.1016/j.bbamem.2022.184072] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 11/13/2022]
Abstract
One of the most distinguished quantities that describes lipid main phase transition, i.e. the transition from the gel (Lβ(')) to the fluid (Lα) phase, is its melting temperature (Tm). Because melting is accompanied by a large change in enthalpy the, Lβ(') → Lα transition can be monitored by various calorimetric, structural and spectroscopic techniques and Tm should be the same regardless of the metric monitored or the technique employed. However, in the case of DPPE multilamellar aggregates there is a small but systematic deviation of Tm values determined by DSC and FTIR spectroscopy. The aim of this paper is to explain this discrepancy by combined UV/Vis spectroscopic and MD computational approach. Multivariate analysis performed on temperature-dependent UV/Vis spectra of DPPE suspensions demonstrated that at 55 ± 1 °C certain phenomenon causes a small but detectable change in suspension turbidity, whereas a dominant change in the latter is registered at 63.2 ± 0.4 °C that coincides with Tm value determined from DSC curve. If this effect should be ignored, the overall data give Tm value the same as FTIR spectra data (61.0 ± 0.4 °C). As the classical MD simulations suggest that about 10° below Tm certain undulations appear at the surface of DPPE bilayers, we concluded that certain discontinuities in curvature fluctuations arise at reported temperature which are to some extent coupled with lipid melting. Ultimately, such events and the associated changes in curvature affect Tm value measured by different techniques.
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Affiliation(s)
- Petra Maleš
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Marija Butumović
- Division of Analytical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia
| | - Ina Erceg
- Division for Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Zlatko Brkljača
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
| | - Danijela Bakarić
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
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7
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van Aalst EJ, Borcik CG, Wylie BJ. Spectroscopic signatures of bilayer ordering in native biological membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183891. [PMID: 35217001 PMCID: PMC10793244 DOI: 10.1016/j.bbamem.2022.183891] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Membrane proteins and polycyclic lipids like cholesterol and hopanoids coordinate phospholipid bilayer ordering. This phenomenon manifests as partitioning of the liquid crystalline phase into liquid-ordered (Lo) and liquid-disordered (Ld) regions. In Eukaryotes, microdomains are rich in cholesterol and sphingolipids and serve as signal transduction scaffolds. In Prokaryotes, Lo microdomains increase pathogenicity and antimicrobial resistance. Previously, we identified spectroscopically distinct chemical shift signatures for all-trans (AT) and trans-gauche (TG) acyl chain conformations, cyclopropyl ring lipids (CPR), and hopanoids in prokaryotic lipid extracts and used Polarization Transfer (PT) SSNMR to investigate bilayer ordering. To investigate how these findings relate to native bilayer organization, we interrogate whole cell and whole membrane extract samples of Burkholderia thailendensis to investigate bilayer ordering in situ. In 13C-13C 2D SSNMR spectra, we assigned chemical shifts for lipid species in both samples, showing conservation of lipids of interest in our native membrane sample. A one-dimensional temperature series of PT SSNMR and transverse relaxation measurements of AT versus TG acyl conformations in the membrane sample confirm bilayer ordering and a broadened phase transition centered at a lower-than-expected temperature. Bulk protein backbone Cα dynamics and correlations consistent with lipid-protein contacts within are further indicative of microdomain formation and lipid ordering. In aggregate, these findings provide evidence for microdomain formation in vivo and provide insight into phase separation and transition mechanics in biological membranes.
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Affiliation(s)
- Evan J van Aalst
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Collin G Borcik
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA
| | - Benjamin J Wylie
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79415, USA.
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8
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Maleš P, Brkljača Z, Domazet Jurašin D, Bakarić D. New spirit of an old technique: Characterization of lipid phase transitions via UV/Vis spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 272:121013. [PMID: 35176647 DOI: 10.1016/j.saa.2022.121013] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/26/2022] [Accepted: 02/04/2022] [Indexed: 06/14/2023]
Abstract
One of the advantages of investigating lipid phase transitions by thermoanalytical techniques such as DSC is manifested in the proportionality of the signal strength on a DSC curve, attributed to a particular thermotropic event, and its cooperativity degree. Accordingly, the pretransition of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) is less noticeable than its main phase transition; as a matter of fact, when DSC measurements are performed at low heating rate, such low-cooperativity phase transition could go (almost) unnoticed. The aim of this work is to present temperature-dependent UV/Vis spectroscopy, based on a temperature-dependent change in DPPC suspension turbidity, as a technique applicable for determination of lipid phase transition temperatures. Multivariate analyzes of the acquired UV/Vis spectra show that phase transitions of the low-cooperativity degree, such as pretransitions, can be identified with the same certainty as transitions of a high-cooperativity degree.
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Affiliation(s)
- Petra Maleš
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, Zagreb 10000, Croatia
| | - Zlatko Brkljača
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, Zagreb 10000, Croatia
| | - Darija Domazet Jurašin
- Division for Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, Zagreb 10000, Croatia
| | - Danijela Bakarić
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, Zagreb 10000, Croatia.
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9
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Stelter D, Keyes T. Membrane Phase Transitions in Lipid-Wrapped Nanoparticles. J Phys Chem B 2022; 126:2507-2512. [DOI: 10.1021/acs.jpcb.1c10903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David Stelter
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Tom Keyes
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
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10
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Sharma P, Desikan R, Ayappa KG. Evaluating Coarse-Grained MARTINI Force-Fields for Capturing the Ripple Phase of Lipid Membranes. J Phys Chem B 2021; 125:6587-6599. [PMID: 34081861 DOI: 10.1021/acs.jpcb.1c03277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Phospholipids, which are an integral component of cell membranes, exhibit a rich variety of lamellar phases modulated by temperature and composition. Molecular dynamics (MD) simulations have greatly enhanced our understanding of phospholipid membranes by capturing experimentally observed phases and phase transitions at molecular resolution. However, the ripple (Pβ') membrane phase, observed as an intermediate phase below the main gel-to-liquid crystalline transition with some lipids, has been challenging to capture with MD simulations, both at all-atom and coarse-grained (CG) resolutions. Here, with an aggregate ∼2.5 μs all-atom and ∼122 μs CGMD simulations, we systematically assess the ability of six CG MARTINI 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid and water force-field (FF) variants, parametrized to capture the DPPC gel and fluid phases, for their ability to capture the Pβ' phase, and compared observations with those from an all-atom FF. Upon cooling from the fluid phase to below the phase transition temperature with smaller (380-lipid) and larger (>2200-lipid) MARTINI and all-atom (CHARMM36 FF) DPPC lipid bilayers, we observed that smaller bilayers with both all-atom and MARTINI FFs sampled interdigitated Pβ' and ripple-like states, respectively. However, while all-atom simulations of the larger DPPC membranes exhibited the formation of the Pβ' phase, MARTINI membranes did not sample interdigitated ripple-like states at larger system sizes. We then demonstrated that the ripple-like states in smaller MARTINI membranes were kinetically trapped structures caused by finite size effects rather than being representative of true Pβ' phases. We showed that a MARTINI FF variant that could capture the tilted Lβ' gel phase, a prerequisite for stabilizing the Pβ' phase, was unable to capture the rippled phase upon cooling. Our study reveals that the current MARTINI FFs (including MARTINI3) may require specific reparametrization of the interaction potentials to stabilize lipid interdigitation, a characteristic of the ripple phase.
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Affiliation(s)
- Pradyumn Sharma
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Rajat Desikan
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India.,Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
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11
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Maleš P, Brkljača Z, Crnolatac I, Bakarić D. Application of MCR-ALS with EFA on FT-IR spectra of lipid bilayers in the assessment of phase transition temperatures: Potential for discernment of coupled events. Colloids Surf B Biointerfaces 2021; 201:111645. [PMID: 33647711 DOI: 10.1016/j.colsurfb.2021.111645] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 01/12/2021] [Accepted: 02/13/2021] [Indexed: 10/22/2022]
Abstract
Temperature-dependent transmission FT-IR spectroscopy and DSC measurements were conducted on lipid multibilayers constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine. Lipid multibilayers made from 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, which do not form a ripple phase, were examined as a reference. Spectra were analyzed using multivariate curve resolution technique with alternating least squares and evolving factor analysis (MCR-ALS with EFA) and lipid phase transition temperatures were determined. Polar parts of lipid molecules exert greater response on a ripple phase formation than non-polar ones. However, vibrational signatures of hydrocarbon chains with intramolecular origins display certain qualitative differences that pave the way for future work oriented on uncoupling the events that drive ripple phase formation.
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Affiliation(s)
- Petra Maleš
- Division of Analytical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - Zlatko Brkljača
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Ivo Crnolatac
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Danijela Bakarić
- Division for Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia.
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12
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Salvador-Castell M, Demé B, Oger P, Peters J. Lipid Phase Separation Induced by the Apolar Polyisoprenoid Squalane Demonstrates Its Role in Membrane Domain Formation in Archaeal Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7375-7382. [PMID: 32515591 DOI: 10.1021/acs.langmuir.0c00901] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Archaea synthesize methyl-branched, ether phospholipids, which confer the archaeal membrane exceptional physicochemical properties. A novel membrane organization was proposed recently to explain the thermal and high pressure tolerance of the polyextremophilic archaeon Thermococcus barophilus. According to this theoretical model, apolar molecules could populate the midplane of the bilayer and could alter the physicochemical properties of the membrane, among which is the possibility to form membrane domains. We tested this hypothesis using neutron diffraction on a model archaeal membrane composed of two archaeal diether lipids with phosphocholine and phosphoethanolamine headgroups in the presence of the apolar polyisoprenoid squalane. We show that squalane is inserted in the midplane at a maximal concentration between 5 and 10 mol % and that squalane can modify the lateral organization of the membrane and induces the coexistence of separate phases. The lateral reorganization is temperature- and squalane concentration-dependent and could be due to the release of lipid chain frustration and the induction of a negative curvature in the lipids.
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Affiliation(s)
| | - Bruno Demé
- Institut Laue Langevin, Grenoble Cedex 9 F-38042, France
| | - Phil Oger
- INSA Lyon, Université de Lyon, CNRS, UMR5240, Villeurbanne 69621, France
| | - Judith Peters
- Institut Laue Langevin, Grenoble Cedex 9 F-38042, France
- Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France
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Srivastava A, Debnath A. Asymmetry and Rippling in Mixed Surfactant Bilayers from All-Atom and Coarse-Grained Simulations: Interdigitation and Per Chain Entropy. J Phys Chem B 2020; 124:6420-6436. [DOI: 10.1021/acs.jpcb.0c03761] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Arpita Srivastava
- Department of Chemistry, IIT Jodhpur, Jodhpur 342037, Rajasthan, India
| | - Ananya Debnath
- Department of Chemistry, IIT Jodhpur, Jodhpur 342037, Rajasthan, India
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14
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Unveiling the Uniqueness of Crystal Structure and Crystalline Phase Behavior of Anhydrous Octyl β-D-Glucoside Using Aligned Assembly on a Surface. Polymers (Basel) 2020; 12:polym12030671. [PMID: 32192160 PMCID: PMC7183315 DOI: 10.3390/polym12030671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 11/17/2022] Open
Abstract
Although the anomalous low crystallinity of octyl β-D-glucoside (β-OGlu) was first proposed more than 30 years ago, many fundamental aspects of its crystal structure and of the crystalline phase behavior of the pure substance have remained uncertain. In this paper, we employ grazing-incidence wide-angle X-ray-diffraction measurements using a two-dimensional detector (2D-GI-WAXD) and perpendicularly aligned crystalline films to demonstrate that β-OGlu forms crystal structures consisting of an intermediate phase-like a ripple phase with two large crystal-lattice constants, a and c, comparable to the lengths of its bilayer structures. Furthermore, solid-to-solid phase transitions accompanied by latent heat confirm the existence of a solid-solution-like phase consisting of a crystalline and a liquid-crystal (LC) phase, which persists over a 20 °C temperature range, in a single-component system. In addition, the system forms a superlattice, accompanied by a change in packing of the component sugars in the partial-melting state; this shift is different from the gel-crystal transition observed for a typical lipid system. These facts indicate that even in the crystalline phase formed from a single component, each individual β-OGlu molecule in a single-component phase plays a versatile role in the crystallisation and melting processes. These findings must somewhat explain the specific co-assembling features with proteins of β-OGlu, which has long been used empirically in biochemistry.
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15
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Liu B, Zhang X, Yan D. The responsive behaviors of bilayer membrane under uniaxial mechanical probe. J Chem Phys 2020; 152:104901. [PMID: 32171195 DOI: 10.1063/5.0001784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In experiments, atomic force microscopy technology was used to measure the modulus of the membrane. However, these studies mainly focus on the linear responsive behavior. In the present work, a theoretical study is performed to show the nonlinear responsive behavior, which includes the stretching induced structural transitions. It demonstrates that the structural transition of the bilayer membrane takes place during the stretching process of the mechanical probe. A vertical cylindrical micelle can be obtained by stretching the membrane under deep compression conditions, and the cylindrical micelle can grow continuously along the axial direction. Moreover, under shallow compression conditions, the probe pulls a spherical micelle from the membrane, and then, the membrane returns to flatness. A comprehensive study is performed to show the mechanism of the responsive behaviors of the structural transition during the compression and stretching processes. When the probe acts on the B-rich layer, it is more likely to pull out a regular micelle. However, when the probe acts on the bottom A-rich layer, complex vesicles are more likely to be pulled out from the bilayer membrane. This study provides a comprehensive diagram of the mechanical responsive behavior of the membrane, which would be a guide for an experiment of biomembranes and the design of new self-assembled structures.
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Affiliation(s)
- Baopi Liu
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Xinghua Zhang
- School of Science, Beijing Jiaotong University, Beijing 100044, China
| | - Dadong Yan
- Department of Physics, Beijing Normal University, Beijing 100875, China
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16
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Galimzyanov TR, Bashkirov PV, Blank PS, Zimmerberg J, Batishchev OV, Akimov SA. Monolayerwise application of linear elasticity theory well describes strongly deformed lipid membranes and the effect of solvent. SOFT MATTER 2020; 16:1179-1189. [PMID: 31934707 DOI: 10.1039/c9sm02079a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The theory of elasticity of lipid membranes is used widely to describe processes of cell membrane remodeling. Classically, the functional of a membrane's elastic energy is derived under assumption of small deformations; the membrane is considered as an infinitely thin film. This functional is quadratic on membrane surface curvature, with half of the splay modulus as its proportionality coefficient; it is generally applicable for small deformations only. Any validity of this functional for the regime of strong deformations should be verified experimentally. Recently, research using molecular dynamics simulations challenged the validity of this classic, linear model, i.e. the constancy of the splay modulus for strongly bent membranes. Here we demonstrate that the quadratic energy functional still can be applied for calculation of the elastic energy of strongly deformed membranes without introducing higher order terms with additional elastic moduli, but only if applied separately for each lipid monolayer. For cylindrical membranes, both classic and monolayerwise models yield equally accurate results. For cylindrical deformations we experimentally show that the elastic energy of lipid monolayers is additive: a low molecular weight solvent leads to an approximately twofold decrease in the membrane bending stiffness. Accumulation of solvent molecules in the inner monolayer of a membrane cylinder can explain these results, as the solvent partially prevents lipid molecules from splaying there. Thus, the linear theory of elasticity can be expanded through the range from weak to strong deformations-its simplicity and physical transparency describe various membrane phenomena.
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Affiliation(s)
- Timur R Galimzyanov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, Moscow 119071, Russia
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17
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Gu RX, Baoukina S, Tieleman DP. Phase Separation in Atomistic Simulations of Model Membranes. J Am Chem Soc 2020; 142:2844-2856. [DOI: 10.1021/jacs.9b11057] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Svetlana Baoukina
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - D. Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
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18
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Walter V, Ruscher C, Benzerara O, Marques CM, Thalmann F. A machine learning study of the two states model for lipid bilayer phase transitions. Phys Chem Chem Phys 2020; 22:19147-19154. [DOI: 10.1039/d0cp02058c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Machine learning algorithms can identify fluid and gel conformation states of individual lipid molecules.
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Affiliation(s)
- Vivien Walter
- Department of Chemistry
- King's College London
- London
- UK
| | - Céline Ruscher
- Stewart Blusson Quantum Matter Institute
- University of British Columbia
- Vancouver
- Canada
| | - Olivier Benzerara
- Institut Charles Sadron
- CNRS and University of Strasbourg
- F-67034 Strasbourg
- France
| | - Carlos M. Marques
- Institut Charles Sadron
- CNRS and University of Strasbourg
- F-67034 Strasbourg
- France
| | - Fabrice Thalmann
- Institut Charles Sadron
- CNRS and University of Strasbourg
- F-67034 Strasbourg
- France
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19
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Devanand T, Krishnaswamy S, Vemparala S. Interdigitation of Lipids Induced by Membrane–Active Proteins. J Membr Biol 2019; 252:331-342. [DOI: 10.1007/s00232-019-00072-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/29/2019] [Indexed: 12/18/2022]
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20
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Meinhardt S, Schmid F. Structure of lateral heterogeneities in a coarse-grained model for multicomponent membranes. SOFT MATTER 2019; 15:1942-1952. [PMID: 30662989 DOI: 10.1039/c8sm02261e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the lateral domain structure in a coarse-grained molecular model for multicomponent lipid bilayers by semi-grandcanonical Monte Carlo simulations. The membranes are filled with liquid ordered (lo) domains surrounded by a liquid disordered (ld) matrix. Depending on the membrane composition and temperature, we identify different morphological regimes: one regime (I) where the lo domains are small and relatively compact, and two regimes (II, II') where they are larger and often interconnected. In the latter two regimes, the ld matrix forms a network of disordered trenches separating the lo domains, with a relatively high content of interdigitated line defects. Since such defects are also a structural element of the modulated ripple phase in one component membranes, we argue that the regimes II, II' may be amorphous equivalents of the ripple phase in multicomponent membranes. We also analyze the local structure and provide evidence that the domains in regime I are stabilized by a monolayer curvature mechanism postulated in earlier work [S. Meinhardt et al., PNAS, 2013, 110, 4476].
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Affiliation(s)
- Sebastian Meinhardt
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, USA
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21
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Nyrkova IA, Semenov AN. The concept of strongly interacting groups in self-assembly of soft matter. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:103. [PMID: 30194515 DOI: 10.1140/epje/i2018-11699-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/10/2018] [Indexed: 06/08/2023]
Abstract
Amphiphilic molecules in solution typically produce structures coming from cooperative interactions of many synergetically acting functional units. If all essential interactions are weak, the structure can be treated theoretically based on a free energy expansion for small interaction parameters. However, most self-assembling soft matter systems involve strong specific interactions of functional units leading to qualitatively new structures of highly soluble micellar or fibrillar aggregates. Here we focus on the systems with the so-called strongly interacting groups (SIGs) incorporated into unimer molecules and discuss the effects of packing frustrations and unimer chirality as well as the origins of spontaneous morphological chirality in the case of achiral unimers. We describe several theoretical approaches (overcoming the limitations of weak interaction models) including the concepts of super-strong segregation, geometrical mismatch and orientational frustration. We also review some recently developed phenomenological theories of surfactant membranes and multiscale hierarchical approaches based on all-atomic modeling of packing structures of amphiphilic molecules with SIGs. In particular, we discuss self-assembling structures in systems possessing simultaneously several distinct types of SIGs: solutions of beta-sheet oligopeptides (showing different fibrillar morphologies), aromatic diamide-ester molecules (forming membranes, helical ribbons and tubules), and triarylamine amide derivatives (producing light-controlled supramolecular nanowires).
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Affiliation(s)
- I A Nyrkova
- Institut Charles Sadron, CNRS - UPR 22, Université de Strasbourg, 23 rue du Loess, BP 84047, 67034, Strasbourg Cedex 2, France
| | - A N Semenov
- Institut Charles Sadron, CNRS - UPR 22, Université de Strasbourg, 23 rue du Loess, BP 84047, 67034, Strasbourg Cedex 2, France.
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22
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Khakbaz P, Klauda JB. Investigation of phase transitions of saturated phosphocholine lipid bilayers via molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1489-1501. [DOI: 10.1016/j.bbamem.2018.04.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/01/2022]
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23
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Lips D, Maass P. Stress-stress fluctuation formula for elastic constants in the NPT ensemble. Phys Rev E 2018; 97:053002. [PMID: 29906955 DOI: 10.1103/physreve.97.053002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Indexed: 11/07/2022]
Abstract
Several fluctuation formulas are available for calculating elastic constants from equilibrium correlation functions in computer simulations, but the ones available for simulations at constant pressure exhibit slow convergence properties and cannot be used for the determination of local elastic constants. To overcome these drawbacks, we derive a stress-stress fluctuation formula in the NPT ensemble based on known expressions in the NVT ensemble. We validate the formula in the NPT ensemble by calculating elastic constants for the simple nearest-neighbor Lennard-Jones crystal and by comparing the results with those obtained in the NVT ensemble. For both local and bulk elastic constants we find an excellent agreement between the simulated data in the two ensembles. To demonstrate the usefulness of the formula, we apply it to determine the elastic constants of a simulated lipid bilayer.
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Affiliation(s)
- Dominik Lips
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany
| | - Philipp Maass
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany
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24
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Lu T, Guo H. Phase Behavior of Lipid Bilayers: A Dissipative Particle Dynamics Simulation Study. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Teng Lu
- Beijing National Laboratory for Molecular Sciences; Joint Laboratory of Polymer Sciences and Materials; State Key Laboratory of Polymer Physics and Chemistry; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Hongxia Guo
- Beijing National Laboratory for Molecular Sciences; Joint Laboratory of Polymer Sciences and Materials; State Key Laboratory of Polymer Physics and Chemistry; Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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25
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Horochowska M, Cieślik-Boczula K, Rospenk M. Ethanol- and trifluoroethanol-induced changes in phase states of DPPC membranes. Prodan emission-excitation fluorescence spectroscopy supported by PARAFAC analysis. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 192:16-22. [PMID: 29126003 DOI: 10.1016/j.saa.2017.10.071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/05/2017] [Accepted: 10/27/2017] [Indexed: 06/07/2023]
Abstract
It has been shown that Prodan emission-excitation fluorescence spectroscopy supported by Parallel Factor (PARAFAC) analysis is a fast, simple and sensitive method used in the study of the phase transition from the noninterdigitated gel (Lβ') state to the interdigitated gel (LβI) phase, triggered by ethanol and 2,2,2-trifluoroethanol (TFE) molecules in dipalmitoylphosphatidylcholines (DPPC) membranes. The relative contribution of lipid phases with spectral characteristics of each pure phase component has been presented as a function of an increase in alcohol concentration. It has been stated that both alcohol molecules can induce a formation of the LβI phase, but TFE is over six times stronger inducer of the interdigitated phase in DPPC membranes than ethanol molecules. Moreover, in the TFE-mixed DPPC membranes, the transition from the Lβ' to LβI phase is accompanied by a formation of the fluid phase, which most probably serves as a boundary phase between the Lβ' and LβI regions. Contrary to the three phase-state model of TFE-mixed DPPC membranes, in ethanol-mixed DPPC membranes only the two phase-state model has been detected.
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Affiliation(s)
- Martyna Horochowska
- Faculty of Chemistry, University of Wroclaw, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | | | - Maria Rospenk
- Faculty of Chemistry, University of Wroclaw, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
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26
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Isabettini S, Massabni S, Hodzic A, Durovic D, Kohlbrecher J, Ishikawa T, Fischer P, Windhab EJ, Walde P, Kuster S. Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility. Phys Chem Chem Phys 2018; 19:20991-21002. [PMID: 28745755 DOI: 10.1039/c7cp03994h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lanthanide ion (Ln3+) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln3+ deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln3+ chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln3+ complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy3+ and parallel alignment of those containing Tm3+. Moreover, samples with chelated Yb3+ were more alignable than the Tm3+ chelating counterparts. Such a possibility has never been demonstrated for planar Ln3+ chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln3+ complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart optical gels.
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Affiliation(s)
- Stéphane Isabettini
- Laboratory of Food Process Engineering, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland.
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27
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Chabanon M, Stachowiak JC, Rangamani P. Systems biology of cellular membranes: a convergence with biophysics. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2017; 9:10.1002/wsbm.1386. [PMID: 28475297 PMCID: PMC5561455 DOI: 10.1002/wsbm.1386] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 02/02/2017] [Accepted: 02/21/2017] [Indexed: 12/12/2022]
Abstract
Systems biology and systems medicine have played an important role in the last two decades in shaping our understanding of biological processes. While systems biology is synonymous with network maps and '-omics' approaches, it is not often associated with mechanical processes. Here, we make the case for considering the mechanical and geometrical aspects of biological membranes as a key step in pushing the frontiers of systems biology of cellular membranes forward. We begin by introducing the basic components of cellular membranes, and highlight their dynamical aspects. We then survey the functions of the plasma membrane and the endomembrane system in signaling, and discuss the role and origin of membrane curvature in these diverse cellular processes. We further give an overview of the experimental and modeling approaches to study membrane phenomena. We close with a perspective on the converging futures of systems biology and membrane biophysics, invoking the need to include physical variables such as location and geometry in the study of cellular membranes. WIREs Syst Biol Med 2017, 9:e1386. doi: 10.1002/wsbm.1386 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Morgan Chabanon
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
| | - Jeanne C. Stachowiak
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
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28
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Stelter D, Keyes T. Enhanced Sampling of Phase Transitions in Coarse-Grained Lipid Bilayers. J Phys Chem B 2017; 121:5770-5780. [PMID: 28530813 DOI: 10.1021/acs.jpcb.6b11711] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Freezing and melting of dipalmitoylphosphatidylcholine (DPPC) bilayers are simulated in both the explicit (Wet) and implicit solvent (Dry) coarse-grained MARTINI force fields with enhanced sampling, via the isobaric, molecular dynamics version of the generalized replica exchange method (gREM). Phase transitions are described with the entropic viewpoint, based upon the statistical temperature as a function of enthalpy, TS(H) = 1/(dS(H)/dH), where S is the configurational entropy. Bilayer thickness, area per lipid, and the second-rank order parameter (P2) are calculated vs temperature in the transition range. In a 32-lipid Wet MARTINI system, transitions in the lipid and water subsystems are strongly coupled, giving rise to considerable structure in TS(H) and the need to specify the state of the water when reporting a lipid transition temperature. For gel lipid + liquid water → fluid lipid + liquid water, we find 292.4 K. The small system is influenced by finite-size effects, but it is argued that the entropic approach is well suited to revealing them, which will be particularly relevant for studies of finite nanosystems where there is no thermodynamic limit. In a 390-lipid Dry MARTINI system, two-dimensional analogues of the topographies of coexisting states ("subphases") seen in pure fluids are found. They are not seen in the 32-lipid Wet or Dry system, but the Dry lipids show a new type of state with gel in one leaflet and tilted gel in the other. Dry bilayer transition temperatures are 333.3 K (390 lipids) and 338 K (32 lipids), indicating that the 32-lipid system is not too small for a qualitative study of the transition. Physical arguments are given for Dry lipid system size dependence and for the difference between Wet and Dry systems.
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Affiliation(s)
- David Stelter
- Department of Chemistry, Boston University , Boston, Massachusetts 02215, United States
| | - Tom Keyes
- Department of Chemistry, Boston University , Boston, Massachusetts 02215, United States
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29
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Schmid F. Physical mechanisms of micro- and nanodomain formation in multicomponent lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:509-528. [PMID: 27823927 DOI: 10.1016/j.bbamem.2016.10.021] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/19/2016] [Accepted: 10/27/2016] [Indexed: 12/17/2022]
Abstract
This article summarizes a variety of physical mechanisms proposed in the literature, which can generate micro- and nanodomains in multicomponent lipid bilayers and biomembranes. It mainly focusses on lipid-driven mechanisms that do not involve direct protein-protein interactions. Specifically, it considers (i) equilibrium mechanisms based on lipid-lipid phase separation such as critical cluster formation close to critical points, and multiple domain formation in curved geometries, (ii) equilibrium mechanisms that stabilize two-dimensional microemulsions, such as the effect of linactants and the effect of curvature-composition coupling in bilayers and monolayers, and (iii) non-equilibrium mechanisms induced by the interaction of a biomembrane with the cellular environment, such as membrane recycling and the pinning effects of the cytoplasm. Theoretical predictions are discussed together with simulations and experiments. The presentation is guided by the theory of phase transitions and critical phenomena, and the appendix summarizes the mathematical background in a concise way within the framework of the Ginzburg-Landau theory. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Friederike Schmid
- Institute of Physics, Johannes Gutenberg University, 55099 Mainz, Germany
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30
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Kim S, Chang R. Structure, Dynamics, and Phase Behavior of DOPC/DSPC Mixture Membrane Systems: Molecular Dynamics Simulation Studies. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Seonghan Kim
- Department of Chemistry; Kwangwoon University; Seoul 01897 Republic of Korea
| | - Rakwoo Chang
- Department of Chemistry; Kwangwoon University; Seoul 01897 Republic of Korea
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31
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Ray S, Kassan A, Busija AR, Rangamani P, Patel HH. The plasma membrane as a capacitor for energy and metabolism. Am J Physiol Cell Physiol 2015; 310:C181-92. [PMID: 26771520 DOI: 10.1152/ajpcell.00087.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
When considering which components of the cell are the most critical to function and physiology, we naturally focus on the nucleus, the mitochondria that regulate energy and apoptotic signaling, or other organelles such as the endoplasmic reticulum, Golgi, ribosomes, etc. Few people will suggest that the membrane is the most critical element of a cell in terms of function and physiology. Those that consider the membrane critical will point to its obvious barrier function regulated by the lipid bilayer and numerous ion channels that regulate homeostatic gradients. What becomes evident upon closer inspection is that not all membranes are created equal and that there are lipid-rich microdomains that serve as platforms of signaling and a means of communication with the intracellular environment. In this review, we explore the evolution of membranes, focus on lipid-rich microdomains, and advance the novel concept that membranes serve as "capacitors for energy and metabolism." Within this framework, the membrane then is the primary and critical regulator of stress and disease adaptation of the cell.
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Affiliation(s)
- Supriyo Ray
- Department of Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, La Jolla, California; and
| | - Adam Kassan
- Department of Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, La Jolla, California; and
| | - Anna R Busija
- Department of Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, La Jolla, California; and
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - Hemal H Patel
- Department of Veterans Affairs San Diego Healthcare System, San Diego, California; Department of Anesthesiology, University of California, San Diego, La Jolla, California; and
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32
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Liu K, Shuai M, Chen D, Tuchband M, Gerasimov JY, Su J, Liu Q, Zajaczkowski W, Pisula W, Müllen K, Clark NA, Herrmann A. Solvent-free Liquid Crystals and Liquids from DNA. Chemistry 2015; 21:4898-903. [PMID: 25712569 DOI: 10.1002/chem.201500159] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Indexed: 01/29/2023]
Abstract
As DNA exhibits persistent structures with dimensions that exceed the range of their intermolecular forces, solid-state DNA undergoes thermal degradation at elevated temperatures. Therefore, the realization of solvent-free DNA fluids, including liquid crystals and liquids, still remains a significant challenge. To address this intriguing issue, we demonstrate that combining DNA with suitable cationic surfactants, followed by dehydration, can be a simple generic scheme for producing these solvent-free DNA fluid systems. In the anhydrous smectic liquid crystalline phase, DNA sublayers are intercalated between aliphatic hydrocarbon sublayers. The lengths of the DNA and surfactant are found to be extremely important in tuning the physical properties of the fluids. Stable liquid-crystalline and liquid phases are obtained in the -20 °C to 200 °C temperature range without thermal degradation of the DNA. Thus, a new type of DNA-based soft biomaterial has been achieved, which will promote the study and application of DNA in a much broader context.
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Affiliation(s)
- Kai Liu
- Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
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33
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Abstract
High resolution structure is presented for the ripple (Pβ') phase of the phospholipid dimyristoylphosphatidylcholine. Low angle X-ray scattering from oriented samples yielded 57 orders, more than twice as many as recorded previously. The determined electron density map has a sawtooth profile similar to the result from lower resolution data, but the features are sharper allowing better estimates for the modulated bilayer profile and the distribution of headgroups along the aqueous interface. Analysis of high resolution wide angle X-ray data shows that the hydrocarbon chains in the longer, major side of the asymmetric sawtooth are packed similarly to the LβF gel phase, with chains in both monolayers coupled and tilted by 18° in the same direction. The absence of Bragg rods that could be associated with the minor side is consistent with disordered chains, as often suggested in the literature. However, the new high resolution bilayer profile strongly suggests that the chains in the two monolayers in the minor side and the curved region are not in registry. This staggered monolayer modulated melting suggests a direction for improving theories of the ripple phase.
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Affiliation(s)
- Kiyotaka Akabori
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA. 15213, USA.
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34
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Rangamani P, Steigmann DJ. Variable tilt on lipid membranes. Proc Math Phys Eng Sci 2014; 470:20140463. [PMID: 25484606 DOI: 10.1098/rspa.2014.0463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 09/17/2014] [Indexed: 11/12/2022] Open
Abstract
A continuum theory for lipid membranes is developed that accounts for mechanical interactions between lipid tilt and membrane shape. For planar membranes, a linear version of the theory is used to predict tilt variations similar to those observed in experiments and molecular dynamics simulations.
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Affiliation(s)
- P Rangamani
- Department of Molecular and Cell Biology , University of California , Berkeley, CA 94720, USA
| | - D J Steigmann
- Department of Mechanical Engineering , University of California , Berkeley, CA 94720, USA
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35
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Toppozini L, Meinhardt S, Armstrong CL, Yamani Z, Kučerka N, Schmid F, Rheinstädter MC. Structure of Cholesterol in Lipid Rafts. PHYSICAL REVIEW LETTERS 2014; 113:228101. [PMID: 25494092 DOI: 10.1103/physrevlett.113.228101] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Indexed: 06/04/2023]
Abstract
Rafts, or functional domains, are transient nano-or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking, and lipid or protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules, we observe raftlike structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raftlike structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers.
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Affiliation(s)
- Laura Toppozini
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | - Sebastian Meinhardt
- KOMET 331, Institute of Physics, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Clare L Armstrong
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | - Zahra Yamani
- Canadian Neutron Beam Centre, Chalk River, Ontario, K0J 1J0, Canada
| | - Norbert Kučerka
- Canadian Neutron Beam Centre, Chalk River, Ontario, K0J 1J0, Canada and Faculty of Pharmacy, Comenius University, 832 32 Bratislava, Slovakia
| | - Friederike Schmid
- KOMET 331, Institute of Physics, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada and Canadian Neutron Beam Centre, Chalk River, Ontario, K0J 1J0, Canada
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36
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Debnath A, Thakkar FM, Maiti PK, Kumaran V, Ayappa KG. Laterally structured ripple and square phases with one and two dimensional thickness modulations in a model bilayer system. SOFT MATTER 2014; 10:7630-7637. [PMID: 25130991 DOI: 10.1039/c4sm01031k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Molecular dynamics simulations of bilayers in a surfactant/co-surfactant/water system with explicit solvent molecules show formation of topologically distinct gel phases depending upon the bilayer composition. At low temperatures, the bilayers transform from the tilted gel phase, Lβ', to the one dimensional (1D) rippled, Pβ' phase as the surfactant concentration is increased. More interestingly, we observe a two dimensional (2D) square phase at higher surfactant concentration which, upon heating, transforms to the gel Lβ' phase. The thickness modulations in the 1D rippled and square phases are asymmetric in two surfactant leaflets and the bilayer thickness varies by a factor of ∼2 between maximum and minimum. The 1D ripple consists of a thinner interdigitated region of smaller extent alternating with a thicker non-interdigitated region. The 2D ripple phase is made up of two superimposed square lattices of maximum and minimum thicknesses with molecules of high tilt forming a square lattice translated from the lattice formed with the thickness minima. Using Voronoi diagrams we analyze the intricate interplay between the area-per-head-group, height modulations and chain tilt for the different ripple symmetries. Our simulations indicate that composition plays an important role in controlling the formation of low temperature gel phase symmetries and rippling accommodates the increased area-per-head-group of the surfactant molecules.
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Affiliation(s)
- Ananya Debnath
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India.
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37
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Schmid F, Dolezel S, Lenz O, Meinhardt S. On ripples and rafts: Curvature induced nanoscale structures in lipid membranes. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/487/1/012004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Harb F, Simon A, Tinland B. Ripple formation in unilamellar-supported lipid bilayer revealed by FRAPP. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:140. [PMID: 24343762 DOI: 10.1140/epje/i2013-13140-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 12/06/2013] [Indexed: 06/03/2023]
Abstract
The mechanisms of formation and conditions of the existence of the ripple phase are fundamental thermodynamic questions with practical implications for medicine and pharmaceuticals. We reveal a new case of ripple formation occurring in unilamellar-supported bilayers in water, which results solely from the bilayer/support interaction, without using lipid mixtures or specific ions. This ripple phase is detected by FRAPP using diffusion coefficient measurements as a function of temperature: a diffusivity plateau is observed. It occurs in the same temperature range where ripple phase existence has been observed using other methods. When AFM experiments are performed in the appropriate temperature range the ripple phase is confirmed.
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Affiliation(s)
- Frédéric Harb
- CNRS, UMR7325, Aix-Marseille Univ., CINaM, 13288, Marseille, France
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39
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Abstract
We review recent computer simulation studies of undulating lipid bilayers. Theoretical interpretations of such fluctuating membranes are most commonly based on generalized Helfrich-type elastic models, with additional contributions of local "protrusions" and/or density fluctuations. Such models provide an excellent basis for describing the fluctuations of tensionless bilayers in the fluid Lαphase at a quantitative level.However, this description is found to fail for membranes in the gel phase and for membranes subject to high tensions. The fluctuations of tilted gel membranes (Lβ′phase) show a signature of the modulated ripple structure Pβ′, which is a nearby phase observed in the pretransition regime between the Lαand Lβ′state. This complicates a quantitative analysis on mesoscopic length scales. In the case of fluid membranes under tension, the large-wavelength fluctuation modes are found to be significantly softer than predicted by theory.In the latter context, we also address the general problem of the relation between frame tension and the fluctuation tension, which has been discussed somewhat controversially in recent years. Simulations of very simple model membranes with fixed area show that the fluctuations should be controlled by the frame tension, and not by the internal tension.
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Affiliation(s)
- FRIEDERIKE SCHMID
- Institute of Physics, Johannes-Gutenberg University of Mainz, D-55099 Mainz, Germany
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40
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Roux M, Sternin E, Bonnet V, Fajolles C, Djedaíni-Pilard F. Dynamic lipid lateral segregation driven by lauryl cyclodextrin interactions at the membrane surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:3677-3687. [PMID: 23409976 DOI: 10.1021/la304524a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Amphiphilic cyclodextrins, with a cholesterol anchor (βChol) or an aspartic acid moiety esterified by two lauryl acyl chains (βDLC), were designed to combine the inclusion ability of the cyclodextrin cavity with the carrier properties of model membranes. Their insertion in phosphatidylcholine bilayers induces a marked lateral phase separation into a pure lipid phase and a cyclodextrin-rich phase (LCD), organized as a 2D cyclodextrin network stabilized by intermolecular hydrogen bonds between the saccharide headgroups at the membrane surface (Roux, M.; Perly, B.; Djedaïni-Pilard, F. Self-Assemblies of Amphiphilic Cyclodextrins. Eur. Biophys. J.2007, 36, 861-867). We have replaced the dilauryl anchor by a single lauryl chain grafted onto a leucine residue, giving monolauryl-β-cyclodextrin (βMLC), which readily inserts into bilayers of chain-deuterated DMPC-d27. The removal of one lauryl acyl chain leads to a dynamic membrane insertion of this new cyclodextrin derivative, with significant lipid exchange on the deuterium NMR time scale between a loosely packed cyclodextrin-enriched phase (L'CD) and free lipid regions, yielding broadened two-component NMR spectra. Like the LCD phases, the cyclodextrin-enriched L'CD regions remain (partially) fluid below the DMPC-d27 main fluid-to-gel transition but do not undergo a clear transition toward a gel state, as observed at 14.5 °C in the LCD phase induced by the dilauryl derivative. Partially fluid lipids of the βMLC-induced L'CD phase coexist with pure lipids in the Pβ' gel phase with possible exchange between them until all of the lipids undergo a transition toward an Lβ' gel state at around 7 °C. Trimethylated monolauryl-β-cyclodextrins induce only an ordering of the lipid acyl chains just above the main transition, without any lateral phase separation. Similar chain ordering is also observed within the βMLC-induced L'CD phase as a consequence of the deep membrane insertion of the monolauryl nonmethylated cyclodextrin derivative.
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Affiliation(s)
- Michel Roux
- CEA/DSV/iBiTec-S, UMR CNRS 8221, SB2SM, F-91191 Gif sur Yvette Cedex, France
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41
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Monolayer curvature stabilizes nanoscale raft domains in mixed lipid bilayers. Proc Natl Acad Sci U S A 2013; 110:4476-81. [PMID: 23487780 DOI: 10.1073/pnas.1221075110] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
According to the lipid raft hypothesis, biological lipid membranes are laterally heterogeneous and filled with nanoscale ordered "raft" domains, which are believed to play an important role for the organization of proteins in membranes. However, the mechanisms stabilizing such small rafts are not clear, and even their existence is sometimes questioned. Here, we report the observation of raft-like structures in a coarse-grained molecular model for multicomponent lipid bilayers. On small scales, our membranes demix into a liquid ordered (lo) phase and a liquid disordered (ld) phase. On large scales, phase separation is suppressed and gives way to a microemulsion-type state that contains nanometer-sized lo domains in an ld environment. Furthermore, we introduce a mechanism that generates rafts of finite size by a coupling between monolayer curvature and local composition. We show that mismatch between the spontaneous curvatures of monolayers in the lo and ld phases induces elastic interactions, which reduce the line tension between the lo and ld phases and can stabilize raft domains with a characteristic size of the order of a few nanometers. Our findings suggest that rafts in multicomponent bilayers might be closely related to the modulated ripple phase in one-component bilayers.
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42
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Computational Studies of Biomembrane Systems: Theoretical Considerations, Simulation Models, and Applications. FROM SINGLE MOLECULES TO NANOSCOPICALLY STRUCTURED MATERIALS 2013. [DOI: 10.1007/12_2013_258] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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43
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Kamal MA, Pal A, Raghunathan VA, Rao M. Phase behavior of two-component lipid membranes: theory and experiments. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:051701. [PMID: 23004773 DOI: 10.1103/physreve.85.051701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Indexed: 06/01/2023]
Abstract
The structure of the ripple phase of phospholipid membranes remains poorly understood in spite of a large number of theoretical studies, with many experimentally established structural features of this phase unaccounted for. In this article we present a phenomenological theory of phase transitions in single- and two-component achiral lipid membranes in terms of two coupled order parameters: a scalar order parameter describing lipid chain melting, and a vector order parameter describing the tilt of the hydrocarbon chains below the chain-melting transition. This model reproduces all the salient structural features of the ripple phase, providing a unified description of the phase diagram and microstructure. In addition, it predicts a variant of this phase that does not seem to have been experimentally observed. Using this model we have calculated generic phase diagrams of two-component membranes. We have also determined the phase diagram of a two-component lipid membrane from x-ray diffraction studies on aligned multilayers. This phase diagram is found to be in good agreement with that calculated from the model.
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Affiliation(s)
- Md Arif Kamal
- Raman Research Institute, C. V. Raman Avenue, Bangalore 560 080, India
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44
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Lai K, Wang B, Zhang Y, Zhang Y. High pressure effect on phase transition behavior of lipid bilayers. Phys Chem Chem Phys 2012; 14:5744-52. [DOI: 10.1039/c2cp24140d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Correlation between the ripple phase and stripe domains in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2849-58. [DOI: 10.1016/j.bbamem.2011.08.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/12/2011] [Accepted: 08/16/2011] [Indexed: 12/19/2022]
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46
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Huang CH, Hsiao PY, Tseng FG, Fan SK, Fu CC, Pan RL. Pore-spanning lipid membrane under indentation by a probe tip: a molecular dynamics simulation study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:11930-42. [PMID: 21859109 DOI: 10.1021/la201977d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We study the indentation of a free-standing lipid membrane suspended over a nanopore on a hydrophobic substrate by means of molecular dynamics simulations. We find that in the course of indentation the membrane bends at the point of contact and the fringes of the membrane glide downward intermittently along the pore edges and stop gliding when the fringes reach the edge bottoms. The bending continues afterward, and the large strain eventually induces a phase transition in the membrane, transformed from a bilayered structure to an interdigitated structure. The membrane is finally ruptured when the indentation goes deep enough. Several local physical quantities in the pore regions are calculated, which include the tilt angle of lipid molecules, the nematic order, the included angle, and the distance between neighboring lipids. The variations of these quantities reveal many detailed, not-yet-specified local structural transitions of lipid molecules under indentation. The force-indentation curve is also studied and discussed. The results make a connection between the microscopic structure and the macroscopic properties and provide deep insight into the understanding of the stability of a lipid membrane spanning over nanopore.
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Affiliation(s)
- Chen-Hsi Huang
- Department of Engineering and System Science, National Tsing Hua University, Taiwan, Republic of China
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47
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Chen R, Poger D, Mark AE. Effect of High Pressure on Fully Hydrated DPPC and POPC Bilayers. J Phys Chem B 2010; 115:1038-44. [DOI: 10.1021/jp110002q] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Rong Chen
- School of Chemistry and Molecular Biosciences and ‡Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - David Poger
- School of Chemistry and Molecular Biosciences and ‡Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Alan E. Mark
- School of Chemistry and Molecular Biosciences and ‡Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
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48
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Jamróz D, Kepczynski M, Nowakowska M. Molecular structure of the dioctadecyldimethylammonium bromide (DODAB) bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:15076-9. [PMID: 20804190 DOI: 10.1021/la102324p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Dioctadecyldimethylammonium bromide (DODAB) is a double-chained quaternary ammonium surfactant that assembles in water into bilayer structures. This letter reports the molecular dynamics (MD) computer simulations of the DODAB bilayer at 25 °C. The simulations show that the surfactant membrane arranges spontaneously into the rippled phase (P(β)(')) at that temperature. The ordering within the chain fragment closest to the hydrophilic head (carbon atoms 1-5) is relatively low. It grows significantly for the carbon atoms located in the center of the membrane (atoms 6-17). The C6-C17 chain fragments are well aligned and tilted by ca. 15° with respect to the bilayer normal.
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Affiliation(s)
- Dorota Jamróz
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland.
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49
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Neder J, West B, Nielaba P, Schmid F. Coarse-grained simulations of membranes under tension. J Chem Phys 2010; 132:115101. [PMID: 20331316 DOI: 10.1063/1.3352583] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigate the properties of membranes under tension by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers. We give a comprising overview of the behavior of several membrane characteristics, such as the area per lipid, the monolayer overlap, the nematic order, and pressure profiles. Both the low-temperature regime, where the membranes are in a gel L(beta(')) phase, and the high-temperature regime, where they are in the fluid L(alpha) phase, are considered. In the L(beta(')) state, the membrane is hardly influenced by tension. In the fluid state, high tensions lead to structural changes in the membrane, which result in different compressibility regimes. The ripple state P(beta(')), which is found at tension zero in the transition regime between L(alpha) and L(beta(')), disappears under tension and gives way to an interdigitated phase. We also study the membrane fluctuations in the fluid phase. In the low-tension regime the data can be fitted nicely to a suitably extended elastic theory. At higher tensions the elastic fit consistently underestimates the strength of long-wavelength fluctuations. Finally, we investigate the influence of tension on the effective interaction between simple transmembrane inclusions and show that tension can be used to tune the hydrophobic mismatch interaction between membrane proteins.
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Affiliation(s)
- Jörg Neder
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
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50
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Mathieu M, Schunk D, Franzka S, Mayer C, Hasselbrink E, Hartmann N. Direct laser patterning of soft matter: photothermal processing of supported phospholipid multilayers with nanoscale precision. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:2099-104. [PMID: 19507151 DOI: 10.1002/smll.200801933] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Direct laser patterning of supported phospholipid multilayers is investigated. Spin coating is used to fabricate stacked bilayers of 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA). Photothermal processing with a focused laser beam at lambda = 514 nm allows removal of the coating at predefined positions without causing any significant change in adjacent areas. Moreover, processing with nanoscale precision is feasible despite the soft and fluid nature of phospholipid films. In particular, holes with diameters from 1.8 microm down to 300 nm and below are fabricated by using a 1/e(2) laser spot size of about 2.5 microm. In addition, patterning is also very flexible and can be carried out over macroscopic length scales and at short processing times. Considering these features photothermal laser processing constitutes a powerful tool for micro- and nanopatterning of phospholipid films.
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Affiliation(s)
- Mareike Mathieu
- Fachbereich Chemie Physikalische Chemie and CeNIDE-Center for Nanointegration Duisburg-Essen, Universität Duisburg-Essen, Essen, Germany
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