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Dymond MK. Lipid monolayer spontaneous curvatures: A collection of published values. Chem Phys Lipids 2021; 239:105117. [PMID: 34265278 DOI: 10.1016/j.chemphyslip.2021.105117] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/03/2021] [Accepted: 07/09/2021] [Indexed: 11/24/2022]
Abstract
Lipid monolayer spontaneous curvatures (or lipid intrinsic curvatures) are one of several material properties of lipids that enable the stored curvature elastic energy in a lipid aggregate to be determined. Stored curvature elastic energy is important since it can modulate the function of membrane proteins and plays a role in the regulatory pathways of phospholipid homeostasis. Due to the large number of different lipid molecules that might theoretically exist in nature, very few lipid spontaneous curvatures have been determined. Herein the values of lipid spontaneous curvatures that exist in the literature are collected, alongside key experimental details. Where possible, trends in the data are discussed and finally, obvious gaps in the knowledge are signposted.
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Affiliation(s)
- Marcus K Dymond
- Chemistry Research and Enterprise Group, School of Pharmacy and Biomolecular Sciences, Huxley Building, University of Brighton, BN2 4GL, United Kingdom.
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2
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Dazzoni R, Grélard A, Morvan E, Bouter A, Applebee CJ, Loquet A, Larijani B, Dufourc EJ. The unprecedented membrane deformation of the human nuclear envelope, in a magnetic field, indicates formation of nuclear membrane invaginations. Sci Rep 2020; 10:5147. [PMID: 32198481 PMCID: PMC7083927 DOI: 10.1038/s41598-020-61746-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/14/2020] [Indexed: 12/04/2022] Open
Abstract
Human nuclear membrane (hNM) invaginations are thought to be crucial in fusion, fission and remodeling of cells and present in many human diseases. There is however little knowledge, if any, about their lipid composition and dynamics. We therefore isolated nuclear envelope lipids from human kidney cells, analyzed their composition and determined the membrane dynamics after resuspension in buffer. The hNM lipid extract was composed of a complex mixture of phospholipids, with high amounts of phosphatidylcholines, phosphatidylinositols (PI) and cholesterol. hNM dynamics was determined by solid-state NMR and revealed that the lamellar gel-to-fluid phase transition occurs below 0 °C, reflecting the presence of elevated amounts of unsaturated fatty acid chains. Fluidity was higher than the plasma membrane, illustrating the dual action of Cholesterol (ordering) and PI lipids (disordering). The most striking result was the large magnetic field-induced membrane deformation allowing to determine the membrane bending elasticity, a property related to hydrodynamics of cells and organelles. Human Nuclear Lipid Membranes were at least two orders of magnitude more elastic than the classical plasma membrane suggesting a physical explanation for the formation of nuclear membrane invaginations.
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Affiliation(s)
- Régine Dazzoni
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.,Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Axelle Grélard
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Estelle Morvan
- Institut Européen de Chimie et Biologie, UMS3033, CNRS, Université Bordeaux, INSERM (US001), 2 rue Escarpit, Pessac, 33600, France
| | - Anthony Bouter
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Christopher J Applebee
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain.,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom
| | - Antoine Loquet
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofísika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, Spain. .,Cell Biophysics Laboratory, Centre for Therapeutic Innovation & Department of Pharmacy and Pharmacology, & Department of Physics, University of Bath, Bath, United Kingdom.
| | - Erick J Dufourc
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR5248, CNRS, Université Bordeaux, INP-Bordeaux, F-33600, Pessac, France.
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3
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Yan XY, Lin Z, Zhang W, Xu H, Guo QY, Liu Y, Luo J, Liu XY, Zhang R, Huang J, Liu T, Su Z, Zhang R, Zhang S, Liu T, Cheng SZD. Magnifying the Structural Components of Biomembranes: A Prototype for the Study of the Self-Assembly of Giant Lipids. Angew Chem Int Ed Engl 2020; 59:5226-5234. [PMID: 31957938 DOI: 10.1002/anie.201916149] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Indexed: 12/24/2022]
Abstract
How biomembranes are self-organized to perform their functions remains a pivotal issue in biological and chemical science. Understanding the self-assembly principles of lipid-like molecules hence becomes crucial. Herein, we report the mesostructural evolution of amphiphilic sphere-rod conjugates (giant lipids), and study the roles of geometric parameters (head-tail ratio and cross-sectional area) during this course. As a prototype system, giant lipids resemble natural lipidic molecules by capturing their essential features. The self-assembly behavior of two categories of giant lipids (I-shape and T-shape, a total of 8 molecules) is demonstrated. A rich variety of mesostructures is constructed in solution state and their molecular packing models are rationally understood. Giant lipids recast the phase behavior of natural lipids to a certain degree and the abundant self-assembled morphologies reveal distinct physiochemical behaviors when geometric parameters deviate from natural analogues.
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Affiliation(s)
- Xiao-Yun Yan
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou, 510640, China.,Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Zhiwei Lin
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Wei Zhang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Hui Xu
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Qing-Yun Guo
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Yuchu Liu
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Jiancheng Luo
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Xian-You Liu
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Jiahao Huang
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Tong Liu
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Zebin Su
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Ruimeng Zhang
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Shuailin Zhang
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Tianbo Liu
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
| | - Stephen Z D Cheng
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou, 510640, China.,Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH, 44325-3909, USA
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4
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Yan X, Lin Z, Zhang W, Xu H, Guo Q, Liu Y, Luo J, Liu X, Zhang R, Huang J, Liu T, Su Z, Zhang R, Zhang S, Liu T, Cheng SZD. Magnifying the Structural Components of Biomembranes: A Prototype for the Study of the Self‐Assembly of Giant Lipids. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201916149] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xiao‐Yun Yan
- South China Advanced Institute for Soft Matter Science and TechnologySchool of Molecular Science and EngineeringSouth China University of Technology Guangzhou 510640 China
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Zhiwei Lin
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Wei Zhang
- South China Advanced Institute for Soft Matter Science and TechnologySchool of Molecular Science and EngineeringSouth China University of Technology Guangzhou 510640 China
| | - Hui Xu
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Qing‐Yun Guo
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Yuchu Liu
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Jiancheng Luo
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Xian‐You Liu
- South China Advanced Institute for Soft Matter Science and TechnologySchool of Molecular Science and EngineeringSouth China University of Technology Guangzhou 510640 China
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and TechnologySchool of Molecular Science and EngineeringSouth China University of Technology Guangzhou 510640 China
| | - Jiahao Huang
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Tong Liu
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Zebin Su
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Ruimeng Zhang
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Shuailin Zhang
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Tianbo Liu
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
| | - Stephen Z. D. Cheng
- South China Advanced Institute for Soft Matter Science and TechnologySchool of Molecular Science and EngineeringSouth China University of Technology Guangzhou 510640 China
- Department of Polymer ScienceCollege of Polymer Science and Polymer EngineeringThe University of Akron Akron OH 44325-3909 USA
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5
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Bouraoui A, Ghanem R, Berchel M, Deschamps L, Vié V, Paboeuf G, Le Gall T, Montier T, Jaffrès PA. Branched lipid chains to prepare cationic amphiphiles producing hexagonal aggregates: supramolecular behavior and application to gene delivery. Org Biomol Chem 2020; 18:337-345. [DOI: 10.1039/c9ob02381j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cationic amphiphiles featuring ramified lipid chains self-organized in water as inverted hexagonal aggregates. They demonstrated high gene delivery efficiencies.
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Affiliation(s)
| | - Rosy Ghanem
- Univ Brest
- INSERM
- groupe “Transfert de gènes et thérapie génique”
- UMR 1078
- CHRU de Brest
| | | | | | | | | | - Tony Le Gall
- Univ Brest
- INSERM
- groupe “Transfert de gènes et thérapie génique”
- UMR 1078
- CHRU de Brest
| | - Tristan Montier
- Univ Brest
- INSERM
- groupe “Transfert de gènes et thérapie génique”
- UMR 1078
- CHRU de Brest
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6
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Orchestration of membrane receptor signaling by membrane lipids. Biochimie 2015; 113:111-24. [DOI: 10.1016/j.biochi.2015.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 04/05/2015] [Indexed: 12/20/2022]
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7
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Fong C, Le T, Drummond CJ. Lyotropic liquid crystal engineering–ordered nanostructured small molecule amphiphileself-assembly materials by design. Chem Soc Rev 2012; 41:1297-322. [DOI: 10.1039/c1cs15148g] [Citation(s) in RCA: 235] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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8
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Characterization and potential applications of nanostructured aqueous dispersions. Adv Colloid Interface Sci 2009; 147-148:333-42. [PMID: 18804754 DOI: 10.1016/j.cis.2008.07.007] [Citation(s) in RCA: 248] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 07/18/2008] [Accepted: 07/30/2008] [Indexed: 11/23/2022]
Abstract
The present article highlights recent advances and current status in the characterization and the utilization of nanostructured aqueous dispersions in which the submicron-sized dispersed particles envelope a distinctive well-defined self-assembled interior. The scope of this review covers dispersions of both inverted-type liquid-crystalline particles (cubosomes, hexosomes, micellar cubosomes, and sponge phases), and microemulsion droplets (emulsified microemulsions, EMEs). Recent investigations that have attempted to shed light on the characterization and the control of confined nanostructures of aqueous dispersions are surveyed, as these nanoobjects are attractive for various pharmaceutical and food applications. The focus has been placed on three main subjects: (1) our findings on the formation of EMEs and the modulation of the internal nanostructure, exploring how variations in temperature, oil content, and lipid composition significantly affect the confined nanostructures; (2) recent developments in the field of electron microscopy: using the tilt-angle cryo-TEM method or cryo-field emission scanning electron microscopy (cryo-FESEM) for observing the three dimensional (3D) morphology of non-lamellar liquid-crystalline nanostructured particles (cubosome and hexosome particles); and (3) recent studies on the utilization of nanostructured dispersions as drug nanocarriers.
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9
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Epand RM. Membrane lipid polymorphism: relationship to bilayer properties and protein function. Methods Mol Biol 2007; 400:15-26. [PMID: 17951724 DOI: 10.1007/978-1-59745-519-0_2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Bilayers are the most familiar arrangement of phospholipids. However, even as bilayers, phospholipids can arrange themselves in a variety of morphologies from essentially flat structures found in large liposomes or when adhered to a flat solid support, to the curved structures found in small liposomes or as bicontinuous cubic phases. Phospholipids can also arrange themselves as curved monolayers, such as in the hexagonal phase, and they can even form spherical or ellipsoid-shaped micelles. A number of factors will determine the final morphology of a lipid aggregate including the structure of the lipid, the nature of the lipid headgroup and its degree of hydration, and the temperature. In addition to being interesting in its own right, the property of lipid polymorphism can be applied to understand how fundamental intrinsic curvature properties of a membrane alter the physical properties of a membrane bilayer. This, in turn, will affect the functional characteristics of membrane proteins, with several possible mechanisms explaining the coupling of membrane properties with protein function.
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Affiliation(s)
- Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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10
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Shearman GC, Ces O, Templer RH, Seddon JM. Inverse lyotropic phases of lipids and membrane curvature. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:S1105-24. [PMID: 21690832 DOI: 10.1088/0953-8984/18/28/s01] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In recent years it has become evident that many biological functions and processes are associated with the adoption by cellular membranes of complex geometries, at least locally. In this paper, we initially discuss the range of self-assembled structures that lipids, the building blocks of biological membranes, may form, focusing specifically on the inverse lyotropic phases of negative interfacial mean curvature. We describe the roles of curvature elasticity and packing frustration in controlling the stability of these inverse phases, and the experimental determination of the spontaneous curvature and the curvature elastic parameters. We discuss how the lyotropic phase behaviour can be tuned by the addition of compounds such as long-chain alkanes, which can relieve packing frustration. The latter section of the paper elaborates further on the structure, geometric properties, and stability of the inverse bicontinuous cubic phases.
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Affiliation(s)
- G C Shearman
- Department of Chemistry, Imperial College London, SW7 2AZ, UK
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11
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Gibson Wood W, Eckert GP, Igbavboa U, Müller WE. Amyloid beta-protein interactions with membranes and cholesterol: causes or casualties of Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1610:281-90. [PMID: 12648781 DOI: 10.1016/s0005-2736(03)00025-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Amyloid beta-protein (Abeta) is thought to be one of the primary factors causing neurodegeneration in Alzheimer's disease (AD). This protein is an amphipathic molecule that perturbs membranes, binds lipids and alters cell function. Several studies have reported that Abeta alters membrane fluidity but the direction of this effect has not been consistently observed and explanations for this lack of consistency are proposed. Cholesterol is a key component of membranes and cholesterol interacts with Abeta in a reciprocal manner. Abeta impacts on cholesterol homeostasis and modification of cholesterol levels alters Abeta expression. In addition, certain cholesterol lowering drugs (statins) appear to reduce the risk of AD in human subjects. However, the role of changes in the total amount of brain cholesterol in AD and the mechanisms of action of statins in lowering the risk of AD are unclear. Here we discuss data on membranes, cholesterol, Abeta and AD, and propose that modification of the transbilayer distribution of cholesterol in contrast to a change in the total amount of cholesterol provides a cooperative environment for Abeta synthesis and accumulation in membranes leading to cell dysfunction including disruption in cholesterol homeostasis.
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Affiliation(s)
- W Gibson Wood
- Geriatric Research, Education and Clinical Center, VA Medical Center, and Department of Pharmacology, University of Minnesota School of Medicine, Minneapolis, MN 55417, USA.
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12
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Koulov AV, Vares L, Jain M, Smith BD. Cationic triple-chain amphiphiles facilitate vesicle fusion compared to double-chain or single-chain analogues. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1564:459-65. [PMID: 12175929 DOI: 10.1016/s0005-2736(02)00496-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cationic, triple-chain amphiphiles promote vesicle fusion more than structurally related double-chain or single-chain analogues. Two types of vesicle fusion experiments were conducted, mixing of oppositely charged vesicles and acid-triggered self-fusion of vesicles composed of cationic amphiphile and anionic cholesteryl hemisuccinate (CHEMS). Vesicle fusion was monitored by standard fluorescence assays for intermembrane lipid mixing, aqueous contents mixing and leakage. Differential scanning calorimetry was used to show that triple-chain amphiphiles lower the lamellar-inverse hexagonal (L(alpha)-H(II)) phase transition temperature for dipalmitoleoylphosphatidylethanolamine. The triple-chain amphiphiles may enhance vesicle fusion because they can stabilize the inversely curved membrane surfaces of the fusion intermediates, however, other factors such as extended conformation, packing defects, chain motion, or surface dehydration may also contribute. From the perspective of drug delivery, the results suggest that vesicles containing cationic, triple-chain amphiphiles (and cationic, cone-shaped amphiphiles in general) may be effective as fusogenic delivery capsules.
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Affiliation(s)
- Atanas V Koulov
- Department of Chemistry and Biochemistry, and the Walther Cancer Research Center, University of Notre Dame, Notre Dame, IN 46556-5670, USA
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13
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Mueller A, O’Brien DF. Supramolecular materials via polymerization of mesophases of hydrated amphiphiles. Chem Rev 2002; 102:727-57. [PMID: 11890755 PMCID: PMC1592244 DOI: 10.1021/cr000071g] [Citation(s) in RCA: 226] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anja Mueller
- C. S. Marvel Laboratories, Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - David F. O’Brien
- C. S. Marvel Laboratories, Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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14
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Abstract
The fusion of two stable bilayers likely proceeds through intermediates in which the membrane acquires curvature. The insertion of peptides into the membrane will affect its curvature tendency. Studies with a number of small viral fusion peptides indicate that these peptides promote negative curvature at low concentration. This is in accord with the curvature requirements to initiate membrane fusion according to the stalk-pore model. Although a characteristic of fusion peptides, the promotion of negative curvature is only one of several mechanisms by which fusion proteins accelerate the rate of fusion. In addition, the fusion peptide itself, as well as other regions in the viral fusion protein, facilitates membrane fusion by mechanisms that are largely independent of curvature. Leakage of the internal aqueous contents of liposomes is another manifestation of the alteration of membrane properties. Peptides exhibit quite different relative potencies between fusion and leakage that is determined by the structure and mode of insertion of the peptide into the membrane.
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Affiliation(s)
- R M Epand
- Department of Biochemistry, McMaster University, Hamilton, Ontario L8N 3Z5 Canada.
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