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Kristensen S, Hassan K, Andersen NS, Steiniger F, Kuntsche J. Feasibility of the preparation of cochleate suspensions from naturally derived phosphatidylserines. FRONTIERS IN MEDICAL TECHNOLOGY 2023; 5:1241368. [PMID: 37745179 PMCID: PMC10512065 DOI: 10.3389/fmedt.2023.1241368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/17/2023] [Indexed: 09/26/2023] Open
Abstract
Introduction Cochleates are cylindrical particles composed of dehydrated phospholipid bilayers. They are typically prepared by addition of calcium ions to vesicles composed of negatively charged phospholipids such as phosphatidylserines (PS). Due to their high physical and chemical stability, they provide an interesting alternative over other lipid-based drug formulations for example to improve oral bioavailability or to obtain a parenteral sustained-release formulation. Methods In the present study, the feasibility to prepare cochleate suspensions from soy lecithin-derived phosphatidylserines (SPS) was investigated and compared to the "gold standard" dioleoyl-phosphatidylserine (DOPS) cochleates. The SPS lipids covered a large range of purities between 53 and >96% and computer-controlled mixing was evaluated for the preparation of the cochleate suspensions. Electron microscopic investigations were combined with small-angle x-ray diffraction (SAXD) and Laurdan generalized polarization (GP) analysis to characterize particle structure and lipid organization. Results Despite some differences in particle morphology, cochleate suspensions with similar internal lipid structure as DOPS cochleates could be prepared from SPS with high headgroup purity (≥96%). Suspensions prepared from SPS with lower purity still revealed a remarkably high degree of lipid dehydration and well-organized lamellar structure. However, the particle shape was less defined, and the typical cochleate cylinders could only be detected in suspensions prepared with higher amount of calcium ions. Finally, the study proves the feasibility to prepare suspensions of cochleates or cochleate-like particles directly from a calcium salt of soy-PS by dialysis.
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Affiliation(s)
- Søren Kristensen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Khadeija Hassan
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | | | - Frank Steiniger
- Center for Electron Microscopy, Jena University Hospital, Jena, Germany
| | - Judith Kuntsche
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
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2
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Cochleate drug delivery systems: An approach to their characterization. Int J Pharm 2021; 610:121225. [PMID: 34710542 DOI: 10.1016/j.ijpharm.2021.121225] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/02/2021] [Accepted: 10/20/2021] [Indexed: 12/18/2022]
Abstract
Cochleate systems formed from phospholipids have very useful properties as drug delivery systems with sustained release capabilities, which are able to improve bioavailability and efficacy, reduce toxicity and increase the shelf-life of encapsulated molecules. These nanometric or micrometric structures are usually obtained after interaction of negatively charged liposomes with a positively charged bridging agent. Many different methods are now available to prepare cochleates and there are also numerous techniques that can be used to characterize them, some of which can be easily applied while others require more sophisticated equipment or analysis. The present review describes the important features of this drug delivery system; including their structural properties and potential applications, as well as a brief account of methods for their preparation and an extensive description of the techniques used for their characterization. This information could guide formulators in their choice of methods of characterization that would be best suited to their needs in terms of time, precision and technological difficulty.
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Large conductance, calcium- and voltage-gated potassium (BK) channels: regulation by cholesterol. Pharmacol Ther 2012; 135:133-50. [PMID: 22584144 DOI: 10.1016/j.pharmthera.2012.05.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 04/09/2012] [Indexed: 11/21/2022]
Abstract
Cholesterol (CLR) is an essential component of eukaryotic plasma membranes. CLR regulates the membrane physical state, microdomain formation and the activity of membrane-spanning proteins, including ion channels. Large conductance, voltage- and Ca²⁺-gated K⁺ (BK) channels link membrane potential to cell Ca²⁺ homeostasis. Thus, they control many physiological processes and participate in pathophysiological mechanisms leading to human disease. Because plasmalemma BK channels cluster in CLR-rich membrane microdomains, a major driving force for studying BK channel-CLR interactions is determining how membrane CLR controls the BK current phenotype, including its pharmacology, channel sorting, distribution, and role in cell physiology. Since both BK channels and CLR tissue levels play a pathophysiological role in human disease, identifying functional and structural aspects of the CLR-BK channel interaction may open new avenues for therapeutic intervention. Here, we review the studies documenting membrane CLR-BK channel interactions, dissecting out the many factors that determine the final BK current response to changes in membrane CLR content. We also summarize work in reductionist systems where recombinant BK protein is studied in artificial lipid bilayers, which documents a direct inhibition of BK channel activity by CLR and builds a strong case for a direct interaction between CLR and the BK channel-forming protein. Bilayer lipid-mediated mechanisms in CLR action are also discussed. Finally, we review studies of BK channel function during hypercholesterolemia, and underscore the many consequences that the CLR-BK channel interaction brings to cell physiology and human disease.
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Epand RF, Sarig H, Ohana D, Papahadjopoulos-Sternberg B, Mor A, Epand RM. Physical Properties Affecting Cochleate Formation and Morphology Using Antimicrobial Oligo-acyl-lysyl Peptide Mimetics and Mixtures Mimicking the Composition of Bacterial Membranes in the Absence of Divalent Cations. J Phys Chem B 2011; 115:2287-93. [DOI: 10.1021/jp111242q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. F. Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - H. Sarig
- Department of Biotechnology & Food Engineering, Technion−Israel Institute of Technology, Haifa, Israel
| | - D. Ohana
- Department of Biotechnology & Food Engineering, Technion−Israel Institute of Technology, Haifa, Israel
| | | | - A. Mor
- Department of Biotechnology & Food Engineering, Technion−Israel Institute of Technology, Haifa, Israel
| | - R. M. Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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Rai PR, Saraph A, Ashton R, Poon V, Mogridge J, Kane RS. Raftlike Polyvalent Inhibitors of the Anthrax Toxin: Modulating Inhibitory Potency by Formation of Lipid Microdomains. Angew Chem Int Ed Engl 2007; 46:2207-9. [PMID: 17310484 DOI: 10.1002/anie.200604317] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Prakash R Rai
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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Rai P, Saraph A, Ashton R, Poon V, Mogridge J, Kane R. Raftlike Polyvalent Inhibitors of the Anthrax Toxin: Modulating Inhibitory Potency by Formation of Lipid Microdomains. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200604317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Rosenberger TA, Farooqui AA, Horrocks LA. Bovine brain diacylglycerol lipase: substrate specificity and activation by cyclic AMP-dependent protein kinase. Lipids 2007; 42:187-95. [PMID: 17393225 DOI: 10.1007/s11745-007-3019-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 01/03/2007] [Indexed: 02/02/2023]
Abstract
Diacylglycerol lipase (EC 3.1.1.3) was purified from bovine brain microsomes using multiple column chromatographic techniques. The purified enzyme migrates as a single band on SDS-PAGE and has an apparent molecular weight of 27 kDa. Substrate specificity experiments using mixed molecular species of 1,2-diacyl-sn-glycerols indicate that low concentrations of Ca(2+) and Mg(2+) have no direct effect on enzymic activity and 1,2-diacyl-sn-glycerols are the preferred substrate over 1,3-diacyl-sn-glycerols. The enzyme hydrolyzes stearate in preference to palmitate from the sn-1 position of 1,2-diacyl-sn-glycerols. 1-O-Alkyl-2-acyl-sn-glycerols are not a substrate for the purified enzyme. The native enzyme had a V (max) value of 616 nmol/min mg protein. Phosphorylation by cAMP-dependent protein kinase resulted in a threefold increase in catalytic throughput (V (max) = 1,900 nmol/min mg protein). The substrate specificity and catalytic properties of the bovine brain diacylglycerol lipase suggest that diacylglycerol lipase may regulate protein kinase C activity and 2-arachidonoyl-sn-glycerol levels by rapidly altering the intracellular concentration of diacylglycerols.
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Affiliation(s)
- Thad A Rosenberger
- Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, 501 North Columbia Road, Grand Forks, ND 58203, USA.
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Arseneault M, Lafleur M. Cholesterol sulfate and Ca(2+) modulate the mixing properties of lipids in stratum corneum model mixtures. Biophys J 2006; 92:99-114. [PMID: 17028138 PMCID: PMC1697843 DOI: 10.1529/biophysj.106.090167] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The influence of cholesterol sulfate (CS) and calcium on the phase behavior of lipid mixtures mimicking the stratum corneum (SC) lipids was examined using vibrational spectroscopy. Raman microspectrocopy showed that equimolar mixtures of ceramide, palmitic acid, and cholesterol underwent a phase transition in which, at low temperatures, lipids formed mainly a mosaic of microcrystalline phase-separated domains, and above 45 degrees C, a more fluid and disordered phase in which the three lipid species were more miscible. In the presence of Ca(2+), there was the formation of fatty acid-Ca(2+) complexes that led to domains stable on heating. Consequently, these lipid mixtures remained heterogeneous, and the fatty acid molecules were not extensively involved in the formation of the fluid lipid phase, which included mainly ceramide and cholesterol. However, the presence of CS displaced the association site of Ca(2+) ions and inhibited the formation of domains formed by the fatty acid molecules complexed with Ca(2+) ions. This work reveals that CS and Ca(2+) modulate the lipid mixing properties and the lipid order in SC lipid models. The balance in the equilibria involving Ca(2+), CS, and fatty acids is proposed to have an impact on the organization and the function of the epidermis.
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Structural, mesomorphic and time-resolved studies of biological liquid crystals and lipid membranes using synchrotron X-radiation. ACTA ACUST UNITED AC 2005. [DOI: 10.1007/3540512012_14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Tessier C, Quinn P, Koumanov K, Trugnan G, Rainteau D, Wolf C. Modulation of the phase heterogeneity of aminoglycerophospholipid mixtures by sphingomyelin and monovalent cations: maintenance of the lamellar arrangement in the biological membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2004; 33:513-21. [PMID: 14997357 DOI: 10.1007/s00249-004-0392-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2003] [Revised: 12/10/2003] [Accepted: 01/22/2004] [Indexed: 11/30/2022]
Abstract
The phase behaviour of mixed molecular species of phosphatidylethanolamine, phosphatidylserine and sphingomyelin of biological origin were examined in aqueous co-dispersions using synchrotron X-ray diffraction. The co-dispersions of phospholipids studied were aimed to model the mixing of lipids populating the cytoplasmic and outer leaflets in the resting or "scrambled" activated cell membrane. Mixtures enriched with phosphatidylethanolamine and phosphatidylserine were characterized by a phase separation of non-lamellar phases (cubic and inverted hexagonal) with a lamellar gel phase comprising the most saturated molecular species. Inclusion of sphingomyelin in the mixture resulted in a suppression of the hexagonal-II phase in favour of lamellar phases at temperatures where a proportion of the phospholipid was fluid. The effect was also dependent on the total amount of sphingomyelin in ternary mixtures, and the lamellar phase dominated in mixtures containing more than 30 mol%, irrespective of the relative proportions of phosphatidylserine/sphingomyelin. A transition from gel to liquid-crystal phase was detected by wide-angle scattering during heating scans of ternary mixtures enriched in sphingomyelin and was shown by thermal cycling experiments to be coupled with a hexagonal-II phase to lamellar transition. In such samples there was evidence of a coexistence of non-lamellar phases with a lamellar gel phase. A transition of the gel phase to the fluid state on heating from 35 to 41 degrees C was evidenced by a progressive increase in the lamellar d-spacing. The presence of calcium enhanced the phase separation of a lamellar gel phase from a hexagonal-II phase in mixtures enriched in phosphatidylserine. This effect was counteracted by charge screening with 150 mM NaCl. The effect of sphingomyelin on stabilizing the lamellar phase is discussed in the context of an altered composition in the cytoplasmic/outer leaflets of the plasma membrane resulting from scrambling of the phospholipid distribution. The results suggest that a lamellar structure can be retained by the inward translocation of sphingomyelin in biological membranes. The presence of monovalent cations serves also to stabilize the bilayer in activated cells where a translocation of aminoglycerophospholipids and an influx of calcium occur simultaneously.
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Affiliation(s)
- Cedric Tessier
- Faculté de Médecine Saint Antoine, Inserm U538, 27 rue Chaligny, 75012 Paris, France
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11
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Ahn T, Oh DB, Kim H, Park C. The phase property of membrane phospholipids is affected by the functionality of signal peptides from the Escherichia coli ribose-binding protein. J Biol Chem 2002; 277:26157-62. [PMID: 12004066 DOI: 10.1074/jbc.m203445200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the effects of synthetic signal peptides from the wild-type, export-defective mutant and its revertant species of ribose-binding protein on the phase properties of lipid bilayers. The lateral segregation of phosphatidylglycerol (PG) in the lipid bilayer was detected through quenching between NBD-PGs upon the reconstitution of signal peptide into the liposome made with the Escherichia coli inner membrane composition. The tendency of lipid segregation was highly dependent on the export competency of signal peptides in vivo, with a decreasing order of wild-type, revertant, and mutant species. The colocalizations of pyrene-PG with BODIPY-PG were also induced by the signal peptides, confirming the phase separation of the acidic phospholipid. The wild-type and revertant signal peptides predominantly formed alpha-helical conformations with the presence of acidic phospholipid as determined by circular dichroism spectroscopy. In addition, they restricted the motion of lipid acyl chains as monitored by fluorescence anisotropy of DPH, suggesting a deep penetration of signal peptide into the lipid bilayer. However, the alpha-helical content of mutant signal peptide was only about half that of the wild-type or revertant peptide with a significantly smaller degree of penetration into the bilayer. An association of the defective signal peptides into the membrane was affected by salt extraction, whereas the functional ones were not. The aforementioned results indicate that the functionality of signal peptide is accomplished through its topologies in the membrane and also by its ability to induce lateral segregation of acidic phospholipid. We propose that the clustering of acidic phospholipid by the functional signal peptide is responsible for the formation of non-bilayer membrane structure, thereby promoting an efficient translocation of secretory proteins.
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Affiliation(s)
- Taeho Ahn
- Research Institute of Natural Science, Pai-Chai University, Taejon, 302-735 Korea
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12
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Krolenko SA, Lucy JA. Reversible vacuolation of T-tubules in skeletal muscle: mechanisms and implications for cell biology. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 202:243-98. [PMID: 11061566 DOI: 10.1016/s0074-7696(01)02006-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The majority of investigations of the transverse tubules (T-system) of skeletal muscle have been devoted to their role in excitation-contraction coupling, with particular reference to contact with the sarcoplasmic reticulum and the mechanism of Ca2- release. By contrast, this review is concerned with structural and functional aspects of the vacuolation of T-tubules. It covers experimental procedures used in reversible vacuolation induced by the efflux-influx of glycerol and other small nonelectrolytes, sugars, and ions. The characteristics of the phenomenon, associated alterations in muscle function, and the swelling of analogous structures in nonmuscle cells are considered. Possible functions of reversible vacuolation in water balance, transport, membrane repair, muscle pathology, and fatigue are considered, and the potential application of reversible vacuolation in the transfection of skeletal muscle is discussed. In relation to the possible mechanisms involved in reversible vacuolation, particular attention is given to the dynamic and structural aspects of the opening and closing of T-tubules, the origin of vacuolar membranes, and the localized character of tubular swelling.
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Affiliation(s)
- S A Krolenko
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg
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13
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Nielsen C, Andersen OS. Inclusion-induced bilayer deformations: effects of monolayer equilibrium curvature. Biophys J 2000; 79:2583-604. [PMID: 11053132 PMCID: PMC1301140 DOI: 10.1016/s0006-3495(00)76498-8] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The energetics of protein-induced bilayer deformation in systems with finite monolayer equilibrium curvature were investigated using an elastic membrane model. In this model the bilayer deformation energy delta G(def) has two major components: a compression-expansion component and a splay-distortion component, which includes the consequences of a bilayer curvature frustration due to a monolayer equilibrium curvature, c(0), that is different from zero. For any choice of bilayer material constants, the value of delta G(def) depends on global bilayer properties, as described by the bilayer material constants, as well as the energetics of local lipid packing adjacent to the protein. We introduce this dependence on lipid packing through the contact slope, s, at the protein-bilayer boundary. When c(0) = 0, delta G(def) can be approximated as a biquadratic function of s and the monolayer deformation at the protein/bilayer boundary, u(0): delta G(def) = a(1)u(0)(2) + a(2)u(0)s + a(3)s(2), where a(1), a(2), and a(3) are functions of the bilayer thickness, the bilayer compression-expansion and splay-distortion moduli, and the inclusion radius (this expression becomes exact when the Gaussian curvature component of delta G(def) is negligible). When c(0) not equal 0, the curvature frustration contribution is determined by the choice of boundary conditions at the protein-lipid boundary (by the value of s), and delta G(def) is the sum of the energy for c(0) = 0 plus the curvature frustration-dependent contribution. When the energetic penalty for the local lipid packing can be ignored, delta G(def) will be determined only by the global bilayer properties, and a c(0) > 0 will tend to promote a local inclusion-induced bilayer thinning. When the energetic penalty for local lipid packing is large, s will be constrained by the value of c(0). In a limiting case, where s is determined only by geometric constraints imposed by c(0), a c(0) > 0 will impede such local bilayer thinning. One cannot predict curvature effects without addressing the proper choice of boundary conditions at the protein-bilayer contact surface.
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Affiliation(s)
- C Nielsen
- Department of Physiology and Biophysics, Cornell University, Weill Medical College, New York, New York 10021, USA.
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14
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Hafez IM, Ansell S, Cullis PR. Tunable pH-sensitive liposomes composed of mixtures of cationic and anionic lipids. Biophys J 2000; 79:1438-46. [PMID: 10969005 PMCID: PMC1301037 DOI: 10.1016/s0006-3495(00)76395-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The pH-dependent fusion properties of large unilamellar vesicles (LUVs) composed of binary mixtures of anionic and cationic lipids have been investigated. It is shown that stable LUVs can be prepared from the ionizable anionic lipid cholesteryl hemisuccinate (CHEMS) and the permanently charged cationic lipid N,N-dioleoyl-N, N-dimethylammonium chloride (DODAC) at neutral pH values and that these LUVs undergo fusion as the pH is reduced. The critical pH at which fusion was observed (pH(f)) was dependent on the cationic lipid-to-anionic lipid ratio. LUVs prepared from DODAC/CHEMS mixtures at molar ratios of 0 to 0.85 resulted in vesicles with pH(f) values that ranged from pH 4.0 to 6.7, respectively. This behavior is consistent with a model in which fusion occurs at pH values such that the DODAC/CHEMS LUV surface charge is zero. Related behavior was observed for LUVs composed of the ionizable cationic lipid 3alpha-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol hydrochloride (DC-Chol) and the acidic lipid dioleoylphosphatidic acid (DOPA). Freeze-fracture and (31)P NMR evidence is presented which indicates that pH-dependent fusion results from a preference of mixtures of cationic and anionic lipid for "inverted" nonbilayer lipid phases under conditions where the surface charge is zero. It is concluded that tunable pH-sensitive LUVs composed of cationic and anionic lipids may be of utility for drug delivery applications. It is also suggested that the ability of cationic lipids to adopt inverted nonbilayer structures in combination with anionic lipids may be related to the ability of cationic lipids to facilitate the intracellular delivery of macromolecules.
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Affiliation(s)
- I M Hafez
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3.
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Huster D, Arnold K, Gawrisch K. Strength of Ca(2+) binding to retinal lipid membranes: consequences for lipid organization. Biophys J 2000; 78:3011-8. [PMID: 10827979 PMCID: PMC1300884 DOI: 10.1016/s0006-3495(00)76839-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There is evidence that membranes of rod outer segment (ROS) disks are a high-affinity Ca(2+) binding site. We were interested to see if the high occurrence of sixfold unsaturated docosahexaenoic acid in ROS lipids influences Ca(2+)-membrane interaction. Ca(2+) binding to polyunsaturated model membranes that mimic the lipid composition of ROS was studied by microelectrophoresis and (2)H NMR. Ca(2+) association constants of polyunsaturated membranes were found to be a factor of approximately 2 smaller than constants of monounsaturated membranes. Furthermore, strength of Ca(2+) binding to monounsaturated membranes increased with the addition of cholesterol, while binding to polyunsaturated lipids was unaffected. The data suggest that the lipid phosphate groups of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) in PC/PE/PS (4:4:1, mol/mol) are primary targets for Ca(2+). Negatively charged serine in PS controls Ca (2+) binding by lowering the electric surface potential and elevating cation concentration at the membrane/water interface. The influence of hydrocarbon chain unsaturation on Ca(2+) binding is secondary compared to membrane PS content. Order parameter analysis of individual lipids in the mixture revealed that Ca(2+) ions did not trigger lateral phase separation of lipid species as long as all lipids remained liquid-crystalline. However, depending on temperature and hydrocarbon chain unsaturation, the lipid with the highest chain melting temperature converted to the gel state, as observed for the monounsaturated phosphatidylethanolamine (PE) in PC/PE/PS (4:4:1, mol/mol) at 25 degrees C.
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Affiliation(s)
- D Huster
- Laboratory of Membrane Biochemistry and Biophysics, NIAAA, National Institutes of Health, Rockville, Maryland 20852, USA
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Cheng Y, Yao H, Lin H, Lu J, Li R, Wang K. The events relating to lanthanide ions enhanced permeability of human erythrocyte membrane: binding, conformational change, phase transition, perforation and ion transport. Chem Biol Interact 1999; 121:267-89. [PMID: 10462058 DOI: 10.1016/s0009-2797(99)00109-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The binding and uptake of Gd3+ ions by human erythrocytes in vitro were studied by determining the Gd contents in membrane and in cytosol by means of particle-induced X-ray emission (PIXE) spectrometry. Results obtained from varied incubation time revealed that the Gd3+ ions bind to the membrane proteins and lipids at first. Gd3+ binding to the membrane lipids and proteins lasts 0 approximately 20 and 20 approximately 100 ms respectively, as shown by the stopped-flow studies. Then a fraction of Gd3+ ions diffuses through the membrane. The kinetics of Gd3+ binding indicates that the binding to phospholipids is prior to that to the membrane proteins, but a portion of the lipid-bound Gd3+ redistributed later to the proteins. PIXE studies showed that the entry of Gd3+ increased the influx of Ca2+ and Cl-. By monitoring the changes in fluorescence of proteins and that of the Ln3+, the uptake of La3+, Eu3+, Gd3+ and Tb3+ was shown to be a process comprising a series of events. Binding to the membrane molecules induces the phase transition of lipid bilayer and conformational changes and aggregation of membrane proteins. Conformational changes of the proteins were characterized by Fourier transform IR spectroscopy (FT-IR) deconvolved spectra, i.e. alpha-helix content decreases while beta-sheet increases. ESR spectra of MSL-labeled proteins reflect the aggregation state related with the conformational change. [31P]NMR spectra of membrane lipid bilayer revealed the Ln3+ ions induced hexagonal (H(II)) phase formation. Phase transition and aggregation of membrane proteins cause the formation of domain structure and perforation in the membrane. These alterations in membrane structure are responsible for the Ln3+ enhanced membrane permeability. Thus the previous Ln3+ binding will facilitate the across-membrane transport of other Ln3+ ions through the membrane.
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Affiliation(s)
- Y Cheng
- National Research Laboratories of Natural and Biomimetic Drugs, Beijing Medical University, China
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Mok KW, Cullis PR. Structural and fusogenic properties of cationic liposomes in the presence of plasmid DNA. Biophys J 1997; 73:2534-45. [PMID: 9370447 PMCID: PMC1181155 DOI: 10.1016/s0006-3495(97)78282-1] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The structural and fusogenic properties of large unilamellar vesicles (LUVs) composed of the cationic lipid N-[2,3-(dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dioleoyl-3-phosphatidylethanotamine (DOPE) have been examined in the presence of pCMV5 plasmid and correlated with transfection potency. It is shown, employing lipid mixing fusion assays, that pCMV5 plasmid strongly promotes fusion between DOTMA/DOPE (1:1) LUVs and DOTMA/1,2-dioleoyl-3-phosphatidylcholine (DOTMA/DOPC) (1:1) LUVs such that at a cationic lipid-to-DNA charge ratio of 3.0, approximately 80% fusion is observed. The anions citrate and chloride can also trigger fusion, but at much higher concentrations. Freeze-fracture electron microscopy studies demonstrate the tendency of cationic vesicles to form clusters at low pCMV5 content, whereas macroscopic fused aggregates can be observed at higher plasmid levels. 31P NMR studies of the fused DNA-DOTMA/DOPE (1:1) complexes obtained at high plasmid levels (charge ratio 1.0) reveal narrow "isotropic" 31P NMR resonances, whereas the corresponding DOPC containing systems exhibit much broader "bilayer" 31P NMR spectra. In agreement with previous studies, the transfection potency of the DOPE-containing systems is dramatically higher than for the DOPC-containing complexes, indicating a correlation between transfection potential and the motional properties of endogenous lipids. Interestingly, it was found that the complexes could be separated by centrifugation into a pellet fraction, which exhibits superior transfection potencies, and a supernatant fraction. Again, the pellet fraction in the DOPE-containing system exhibits a significantly narrower 31P NMR resonance than the corresponding DOPC-containing system. It is suggested that the 31P NMR characteristics of complexes exhibiting higher transfection potencies are consistent with the presence of nonbilayer lipid structures, which may play a direct role in the fusion or membrane destabilization events vital to transfection.
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Affiliation(s)
- K W Mok
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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Stubbs CD, Slater SJ. The effects of non-lamellar forming lipids on membrane protein-lipid interactions. Chem Phys Lipids 1996; 81:185-95. [PMID: 8810048 DOI: 10.1016/0009-3084(96)02581-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of lipid polymorphism in the regulation of membrane-associated protein function is examined, based on recent studies which showed that changes in the levels of phosphatidylethanolamine (PE), cholesterol and phospholipid unsaturation, modulate the activity of the key signal transduction enzyme, protein kinase C (PKC). It is shown that effects of membrane compositional changes on PKC activity involve a perturbation of protein-lipid interactions with the head group region rather than with the hydrophobic interior of the bilayer. A key determinant in the perturbation of these interactions is suggested to be an elastic curvature energy, termed curvature stress, which results from the unfavorable packing of non-lamellar forming lipids in a planar bilayer. PKC activity is shown to be a biphasic function of curvature stress, with an optimum value of this parameter corresponding to an optimally active PKC conformation. Thus, it is shown that the maximal activity of conformationally distinct PKC isoforms may require a different optimum value of curvature stress. Furthermore, it is hypothesized that curvature stress may have differing effects on the conformation of membrane-associated PKC activity induced by diacylglycerols, phorbol esters or other activators, based on recent studies showing that these agents induce the formation of disparate active conformers of the enzyme.
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Affiliation(s)
- C D Stubbs
- Department of Anatomy, Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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19
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Wegener J, Galla HJ. The role of non-lamellar lipid structures in the formation of tight junctions. Chem Phys Lipids 1996. [DOI: 10.1016/0009-3084(96)02585-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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20
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Abstract
The physical concepts underlying the lateral distribution of the components forming a lamellar assembly of amphiphiles are discussed in this review. The role of amphiphiles' molecular structure and/or aqueous environment (ionic strength, water soluble substances) on formation and stability of lateral patterns is investigated. A considerable effort is devoted to the analysis of the properties of patterned structure which can be different from those of randomly mixed multi-component lamellae. Examples include adhesion and fusion among laterally inhomogeneous bilayers, enhanced interfacial adsorption of ions and polymers, enhanced transport across the bilayer, modified mechanical properties, local stabilization of non-planar geometries (pores, edges) and related phenomena (electroporation, budding transition and so on). Furthermore, an analysis of chemical reactivity within or at the water interface of a laterally inhomogeneous bilayer is briefly discussed. A link between these concepts and experimental findings taken from the biological literature is attempted throughout the review.
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Affiliation(s)
- A Raudino
- Dipartimento di Scienze Chimiche, Università di Catania, Italy
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21
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Coorssen JR, Rand RP. Structural effects of neutral lipids on divalent cation-induced interactions of phosphatidylserine-containing bilayers. Biophys J 1995; 68:1009-18. [PMID: 7756521 PMCID: PMC1281824 DOI: 10.1016/s0006-3495(95)80276-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Ca2+ is known to induce the adhesion and collapse of phosphatidylserine (PS) bilayers into dehydrated multilamellar structures. The aim of this study was to examine how that interaction and the resultant structures might be modified by neutral lipid species. A combination of rapid mixing, x-ray diffraction, thin-layer chromatography, density gradient centrifugation, and freeze-fracture electron microscopy was used in conjunction with osmotic stress techniques to characterize the structures formed by the Ca(2+)-induced interaction of multilamellar liposomes and of large unilamellar vesicles. The results showed that dioleoylphosphatidylcholine and dioleoylphosphatidylethanolamine at concentrations of up to approximately 30 mol % are accommodated in a single dehydrated multilamellar structure. Similar results were obtained using mixed PS species isolated from bovine brain. Principally, the data indicate that neutral lipid is both dehydrated during the rapid collapse process of Ca(PS)2 formation and accommodated within this dehydrated structure. The large energies available on formation of the Ca(PS)2 bilayers contribute to the dehydration of neighboring neutral lipids that likely form continuous bilayers with them. Higher concentrations of these neutral lipids modify Ca(2+)-induced bilayer interactions, leading to progressively weaker interactions, larger bilayer separations, and in some cases separation into two structures; phosphatidylethanolamine species favoring nonbilayer structures tended to promote such separation at lower concentrations than bilayer lipids.
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Affiliation(s)
- J R Coorssen
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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22
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Mechanisms underlying taurine-mediated alterations in membrane function. Amino Acids 1995; 8:231-46. [DOI: 10.1007/bf00806821] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1994] [Accepted: 08/03/1994] [Indexed: 10/26/2022]
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23
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Chang HM, Reitstetter R, Mason RP, Gruener R. Attenuation of channel kinetics and conductance by cholesterol: an interpretation using structural stress as a unifying concept. J Membr Biol 1995; 143:51-63. [PMID: 7714888 DOI: 10.1007/bf00232523] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The ubiquity of cholesterol in cell membranes and changes in its concentration during development, aging and in various diseases suggest that it plays an important role in modulating cell function. We examined this possibility by monitoring the effects of cholesterol on the activity of the calcium-activated potassium (BK) channel reconstituted into lipid bilayers from rat brain homogenates. Increasing the cholesterol concentration to 11% of total lipid weight resulted in a 70% reduction in channel mean open time and a reduction of the open probability of the channel by 80%. Channel conductance was reduced by 7%. Cholesterol is known to change the order state and the modulus of compressibility of bilayers. These physico-chemical changes may be translated into an overall increase in the structural stress in the bilayer, and this force may be transmitted to proteins residing therein. By examining the characteristics of the BK channel as a function of temperature, in the presence and absence of cholesterol, we were able to estimate the activation energy based on Arrhenius plots of channel kinetics. Cholesterol reduced the activation energy of the BK channel by 50% for the open to closed transition. This result is consistent with an increased stress energy in the bilayer and favors the channel moving into the closed state. Taken together, these data are consistent with a model in which cholesterol induces structural stress which enhances the transition from the open to the closed state of the channel. We suggest that this is an important mechanism for regulating the activity of membrane-integral proteins and therefore membrane function, and that the concept of structural stress may be relevant to understanding the modulation of ion channel activity in cell membranes.
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Affiliation(s)
- H M Chang
- University of Arizona College of Medicine, Department of Physiology, Tucson 85724
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24
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Ostolaza H, Bartolomé B, Ortiz de Zárate I, de la Cruz F, Goñi FM. Release of lipid vesicle contents by the bacterial protein toxin alpha-haemolysin. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1147:81-8. [PMID: 7682112 DOI: 10.1016/0005-2736(93)90318-t] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
alpha-Haemolysin is a protein toxin (107 kDa) secreted by some pathogenic strains of E. coli. It binds to mammalian cell membranes, disrupting cellular activities and lysing cells. This paper describes the mechanism of alpha-haemolysin-induced membrane leakage, from experiments in which extrusion large unilamellar vesicles, loaded with fluorescent solutes, are treated with purified toxin. The results show that the toxin does not require of any membrane receptor to exert its activity, that vesicles become leaky following an 'all-or-none' mechanism, and that leakage occurs through a non-osmotic detergent-like bilayer disruption induced by the protein. Small pores formed by monomeric alpha-haemolysin, as described by other authors, do not appear to be related to the process of membrane disruption. Instead, the experimental data would be in agreement with the idea of oligomeric assemblies being required to produce release of solutes from a single vesicle.
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Affiliation(s)
- H Ostolaza
- Department of Biochemistry, University of the Basque Country, Bilbao, Spain
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25
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de Wolf FA, Nicolay K, de Kruijff B. Effect of doxorubicin on the order of the acyl chains of anionic and zwitterionic phospholipids in liquid-crystalline mixed model membranes: absence of drug-induced segregation of lipids into extended domains. Biochemistry 1992; 31:9252-62. [PMID: 1390711 DOI: 10.1021/bi00153a019] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We investigated the effect of the antineoplastic drug doxorubicin on the order of the acyl chains in liquid-crystalline mixed bilayers consisting of dioleoylphosphatidylserine (DOPS) or -phosphatidic acid (DOPA), and dioleoylphosphatidylcholine (DOPC) or -phosphatidylethanolamine (DOPE). Previous 2H-NMR studies on bilayers consisting of a single species of di[11,11-2H2]oleoyl-labeled phospholipid showed that doxorubicin does not affect the acyl chain order of pure zwitterionic phospholipid but dramatically decreases the order of anionic phospholipid [de Wolf, F. A., et al. (1991) Biochim. Biophys. Acta 1096, 67-80]. In the present work, we studied mixed bilayers in which alternatively the anionic or the zwitterionic phospholipid component was 2H-labeled so as to monitor its individual acyl chain order. Doxorubicin decreased the order parameter of the mixed anionic and zwitterionic lipids by approximately the same amount and did not induce a clear segregation of the lipid components into extended, separate domains. The drug had a comparable disordering effect on mixed bilayers of unlabeled cardiolipin and 2H-labeled zwitterionic phospholipid, indicating the absence of extensive segregation also in that case. Upon addition of doxorubicin to bilayers consisting of 67 mol% DOPE and 33 mol% anionic phospholipid, a significant part of the lipid adopted the inverted hexagonal (HII) phase at 25 degrees C. This bilayer destabilization, which occurred only in mixtures of anionic phospholipid and sufficient amounts of DOPE, might be of physiological importance. Even upon formation of extended HII-phase domains, lipid segregation was not clearly detectable, since the relative distribution of 2H-labeled anionic phospholipid and [2H]DOPE between the bilayer phase and HII phase was very similar. Our findings argue against a role of extensive anionic/zwitterionic lipid segregation in the mechanism of action and toxicity of doxorubicin.
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Affiliation(s)
- F A de Wolf
- Institute of Molecular Biology and Medical Biotechnology, University of Utrecht, The Netherlands
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26
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Sellström Å, Gustafson I, Ohlsson PÅ, Olofsson G, Puu G. On the deposition of phospholipids onto planar supports with the Langmuir—Blodgett technique using factorial experimental design 2. Optimizing lipid composition for maximal adhesion to platinum substrates. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0166-6622(92)80108-e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Silvius JR. Anomalous mixing of zwitterionic and anionic phospholipids with double-chain cationic amphiphiles in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1070:51-9. [PMID: 1751538 DOI: 10.1016/0005-2736(91)90145-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
High-sensitivity scanning calorimetry has been used to examine the thermotropic behavior of mixtures combining dipalmitoylphosphatidylcholine (DPPC), phosphatidylethanolamine (DPPE) and O-methylphosphatidic acid (DPPA-OMe) with the double-chain cationic amphiphiles N,N-dihexadecyl-N,N- dimethylammonium chloride (DHDAC), 1,2-dipalmitoyloxy-3-(trimethylammonio)propane (DPTAP) and the corresponding monomethylated tertiary amino compounds (DHMMA-H+ and DPDAP-H+). At physiological ionic strength, mixtures of these cationic amphiphiles with the anionic phospholipid DPPA-OMe can show gel-to-liquid-crystalline phase transitions at considerably higher temperatures than do either of the pure components. Surprisingly, binary mixtures of DPPC and these cationic amphiphiles also show strongly nonideal mixing, with phase diagrams exhibiting pronounced maxima in their solidus and liquidus curves. Similar behavior is not observed for mixtures of DPPC with DPPA-OMe, which closely resembles DPTAP and DPDAP-H+ in backbone configuration and polar headgroup size. The present results suggest that perturbation of the orientation of the phosphatidylcholine headgroup by cationic amphiphiles, as demonstrated previously by Seelig and co-workers (Biochemistry 28 [1989], 7720-7728), can significantly affect the thermotropic behavior of phospholipids such as DPPC. Such effects may exert a generally important (though not always easily recognizable) influence on the organization and thermotropic behavior of systems where zwitterionic phospholipids are combined with charged bilayer-associated molecules.
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Affiliation(s)
- J R Silvius
- Department of Biochemistry, McGill University, Montréal, Québec Canada
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28
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Fenske DB, Letellier M, Roy R, Smith IC, Jarrell HC. Effect of calcium on the dynamic behavior of sialylglycerolipids and phospholipids in mixed model membranes. A 2H and 31P NMR study. Biochemistry 1991; 30:10542-50. [PMID: 1931977 DOI: 10.1021/bi00107a025] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DTSL, a sialic acid bearing glyceroglycolipid, has been deuteriated at the C3 position of the sialic acid headgroup and at the C3 position of the glycerol backbone. The glycolipid was studied as a neat dispersion and in multilamellar dispersions of DMPC (at a concentration of 5-10 mol % relative to phospholipid), using 2H and 31P NMR. The quadrupolar splittings, delta v Q, of the headgroup deuterons were found to differ in the neat and mixed dispersion, suggesting different headgroup orientations in the two systems. In DTSL-DMPC liposomes, two quadrupolar splittings were observed, indicating that the axial and equatorial deuterons make different angles with respect to the axis of motional averaging. The splittings originating from the equatorial and axial deuterons were found to increase and decrease with increasing temperature, respectively, indicating a temperature-dependent change in average headgroup orientation. Longitudinal relaxation times, T1Z, were found to be short (3-6 ms). The field dependence of T1Z suggests that more than one motion governs relaxation. At 30.7 MHz a T1Z minimum was observed at approximately 40 degrees C. At 46.1 MHz the T1Z values were longer and increased with temperature, demonstrating that the dominant rigid-body motions of the headgroup at this field are in the rapid motional regime (greater than 10(8) s-1). DTSL labeled at the glycerol C3 position was studied in DMPC multilamellar dispersions. Whereas two quadrupolar splittings have been observed for other glycolipids labeled at this position, only a single delta nu Q was observed. This shows that the orientation of the C2-C3 segment of DTSL relative to the bilayer normal differs from that of other glycolipids.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D B Fenske
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario
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29
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Choi S, Ware W, Lauterbach SR, Phillips WM. Infrared spectroscopic studies on the phosphatidylserine bilayer interacting with calcium ion: effect of cholesterol. Biochemistry 1991; 30:8563-8. [PMID: 1888723 DOI: 10.1021/bi00099a011] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Fourier transform infrared (IR) spectroscopic studies of phosphatidylserine/cholesterol/Ca2+ complexes are reported using the synthetic phosphatidylserines (PS) 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS). IR spectra reveal that cholesterol does not significantly alter the binding nature of Ca2+ to PS molecules; Ca2+ binds to the phosphate ester group of PS in the presence of cholesterol up to 50 mol% as in the case of pure PS bilayers. However, the IR data indicate that the presence of cholesterol induces disorder of the acyl chain packing, increases the degree of immobilization of the interfacial and polar regions, and increases the degree of dehydration of the PS/Ca2+ complexes.
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Affiliation(s)
- S Choi
- Department of Chemistry and Biochemistry, Middlebury College, Vermont 05753
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30
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Raudino A, Bianciardi P. Lipid immiscibility and structure of the charged membrane—water interface. J Electroanal Chem (Lausanne) 1991. [DOI: 10.1016/0022-0728(91)85568-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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31
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Raudino A, Bianciardi P. Lipid immiscibility and structure of the charged membrane-water interface. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0302-4598(91)87033-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Abstract
The binding of calcium to headgroup deuterated 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphoserine (POPS) was investigated by using deuterium magnetic resonance in pure POPS membranes and in mixed 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC)/POPS 5:1 (m:m) bilayers. Addition of CaCl2 to pure POPS bilayers led to two component spectra attributed, respectively, to liquid-crystallin POPS (less than 15 kHz) and POPS molecules in the calcium-induced dehydrated phase (cochleate) (approximately 120 kHz). The liquid-crystalline component has nearly disappeared at a Ca2+ to POPS ratio of 0.5, indicating that, under such conditions, most of the POPS molecules are in the precipitated cochleate phase. After dilution of the POPS molecules in zwitterionic POPC membranes (POPC/POPS 5:1 m:m), single component spectra characteristic of POPS in the liquid-crystalline state were observed in the presence of Molar concentrations of calcium ions (Ca2+ to POPS ratio greater than 50), showing that the amount of dehydrated cochleate PS-Ca2+ phase, if any, was low (less than 5%) under such conditions. Deuterium NMR data obtained in the 15-50 degrees C temperature range with the mixed PC/PS membranes, either in the absence or the presence of Ca2+ ions, indicate that the serine headgroup undergoes a temperature-induced conformational change, independent of the presence of Ca2+. This is discussed in relation to other headgroup perturbations such as that observed upon change of the membrane surface charge density.
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Affiliation(s)
- M Roux
- Département de Biologie, CEN-Saclay, Gif-sur-Yvette, France
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33
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Macromolecular prodrugs interaction with mixed lipid membrane. A calorimetric study of naproxen linked to polyaspartamide interacting with phosphatidylcholine and phosphatidylcholine-phosphatidic acid vesicles. Int J Pharm 1991. [DOI: 10.1016/0378-5173(91)90162-h] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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34
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Henseleit U, Plasa G, Haest C. Effects of divalent cations on lipid flip-flop in the human erythrocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1029:127-35. [PMID: 2223803 DOI: 10.1016/0005-2736(90)90445-t] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Treatment of human erythrocytes with ionophore A23187 (10 mumol.l-1) and Ca2+ (0.05-0.5 mmol.l-1) or Sr2+ (0.2-1 mmol.l-1) in results in a concentration-dependent acceleration of the transmembrane reorientation (flip) of the lipid probes lysophosphatidylcholine and palmitoylcarnitine to the inner membrane leaflet after their primary insertion into the outer leaflet. Mg2+, Mn2+, Zn2+ and La3+ do not accelerate flip. Ca2(+)-induced flip acceleration depends also on the ionophore concentration. It is reversed by removal of Ca2+ with EDTA. A causal role of Ca2(+)-induced membrane protein degradation and decrease of the polyphosphoinositide level in flip acceleration could be excluded. Likewise, calmodulin-dependent processes are probably not involved since the calmodulin antagonist calmidazolium (2-10 mumol.l-1) does not suppress but even enhances the Ca2(+)-induced flip acceleration. The same is true for the Ca2+ antagonist flunarizine. These drugs do not alter flip rate in the absence of Ca2+. At high Ca2+ (1-5 mmol.l-1) an initial flip acceleration is followed by flip normalization. High concentrations of Mn2+ and Mg2+ slow down flip rates. The selective acceleration of flip by Ca2+ and Sr2+ is discussed to be due to a local detachment of the membrane skeleton from the bilayer, whereas the unselective slow down of flip by divalent cations might be due to a stabilization of the membrane bilayer by the cations. After loading of cells with Ca2+ (but not with Mn2+) the inner membrane leaflet phospholipid phosphatidylserine becomes rapidly exposed to the outer membrane surface, as detectable by its accessibility to phospholipase A2 (5 min).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- U Henseleit
- Institut für Physiologie, Medizinische Fakultät, RWTH Aachen, F.R.G
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35
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Abstract
In conclusion, charged membrane together with their adjacent electrolyte solution form a thermodynamic and physico-chemical entity. Their surfaces represent an exceptionally complicated interfacial system owing to intrinsic membrane complexity, as well as to the polarity and often large thickness of the interfacial region. Despite this, charged membranes can be described reasonably accurately within the framework of available theoretical models, provided that the latter are chosen on the basis of suitable criteria, which are briefly discussed in Section A. Interion correlations are likely to be important for the regular and/or rigid, thin membrane-solution interfaces. Lateral distribution of the structural membrane charge is seldom and charge distribution perpendicular to the membranes is nearly always electrostatically important. So is the interfacial hydration, which to a large extent determines the properties of the innermost part of the interfacial region, with a thickness of 2-3 nm. Fine structure of the ion double-layer and the interfacial smearing of the structural membrane charge decrease whilst the surface hydration increases the calculated value of the electrostatic membrane potential relative to the result of common Gouy-Chapman approximation. In some cases these effects partly cancel-out; simple electrostatic models are then fairly accurate. Notwithstanding this, it is at present difficult to draw detailed molecular conclusions from a large part of the published data, mainly owing to the lack of really stringent controls or calibrations. Ion binding to the membrane surface is a complicated process which involves charge-charge as well as charge-solvent interactions. Its efficiency normally increases with the ion valency and with the membrane charge density, but it is also strongly dependent on the physico-chemical and thermodynamic state of the membrane. Except in the case of the stereospecific ion binding to a membrane, the relatively easily accessible phosphate and carboxylic groups on lipids and integral membrane proteins are the main cation binding sites. Anions bind preferentially to the amine groups, even on zwitterionic molecules. Membrane structure is apt to change upon ion binding but not always in the same direction: membranes with bound ions can either expand or become more condensed, depending on the final hydrophilicity (polarity) of the membrane surface. The more polar membranes, as a rule, are less tightly packed and more fluid. Diffusive ion flow across a membrane depends on the transmembrane potential and concentration gradients, but also on the coulombic and hydration potentials at the membrane surface.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- G Cevc
- Medizinische Biophysik, Technischen Universität München, F.R.G
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36
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Kaufman AE, Goldfine H, Narayan O, Gruner SM. Physical studies on the membranes and lipids of plasmalogen-deficient Megasphaera elsdenii. Chem Phys Lipids 1990; 55:41-8. [PMID: 2208444 DOI: 10.1016/0009-3084(90)90147-j] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Membrane fluidity and thermotropic phase behavior in the wild-type and plasmalogen-deficient strains of Megasphaera elsdenii have been studied by means of diphenylhexatiene steady state fluorescence anisotropy in isolated membranes, and by 31P-NMR and X-ray diffraction of the isolated phospholipids. Compared to the wild-type plasmalogen content of greater than 75%, plasmalogen-deficient strains had less than 5% plasmalogen, consisting largely of phosphatidylethanolamine and phosphatidylserine. Steady state fluorescence anisotropy measurements yielded an order parameter which was 6% lower in the plasmalogen-deficient membranes from 10 degrees to 40 degrees C, indicating higher membrane lipid mobilities. Both 31P-NMR and X-ray diffraction revealed the formation of a hexagonal phase in the lipids from the wild-type strain starting above 30 degrees C. In general the transition was not complete by 80 degrees C. In contrast, phospholipids from plasmalogen-deficient strains appeared to form a relatively stable lamellar phase.
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Affiliation(s)
- A E Kaufman
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia 19104-6076
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37
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Wiedmann TS, Trouard T, Shekar SC, Polikandritou M, Rahman YE. Interaction of cyclosporin A with dipalmitoylphosphatidylcholine. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1023:12-8. [PMID: 2317490 DOI: 10.1016/0005-2736(90)90003-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cyclosporin A, a hydrophobic cyclic peptide, is a potent immunosuppressant. In an attempt to determine the localization of cyclosporin A in phospholipid membranes, the effect of cyclosporin A on dipalmitoylphosphatidylcholine (DPPC) has been investigated using deuterium nuclear magnetic resonance (2H-NMR) spectroscopy and differential scanning calorimetry (DSC). Cyclosporin A was dispersed within acyl chain per-deuterated DPPC at a concentration of 6 mole percent, hydrated with buffer, and the spectra obtained over a range of temperatures were compared with that of pure DPPC. The changes caused by cyclosporin A were assessed by the first moment (M1) and order parameters calculated from the spectra. The presence of cyclosporin A decreases the magnitude of M1 at temperatures below the gel to liquid-crystalline phase transition temperature but increases M1 at temperatures above the transition. In addition, the change in M1 at the transition temperature was also less abrupt when cyclosporin A was present. For bilayers in the liquid-crystalline state, cyclosporin A causes an increase in the order parameters along the acyl chains which suggests that cyclosporin A is located along the acyl chains of the phospholipid. For DSC, cyclosporin A was dispersed in non-deuterated DPPC at different peptide to phospholipid mole ratios. The endothermic peaks associated with the gel to liquid-crystalline phase transition and pretransition were recorded and compared with similar mole ratios of cholesterol to lipid. At 30 mole percent cyclosporin A, small decreases in the main transition temperature and associated enthalpy were observed, whereas at 30 mole percent cholesterol, the main transition is barely distinguishable from the baseline. The pretransition was not observed with the addition of 11 mole percent of either cyclosporin A or cholesterol. The results of the thermal analysis indicate that although cyclosporin A and cholesterol appear to be both located along the acyl chains of the phospholipids, they have dramatically different interactions with the membrane lipids.
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Affiliation(s)
- T S Wiedmann
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis 55455
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38
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Seddon JM. Structure of the inverted hexagonal (HII) phase, and non-lamellar phase transitions of lipids. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1031:1-69. [PMID: 2407291 DOI: 10.1016/0304-4157(90)90002-t] [Citation(s) in RCA: 775] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- J M Seddon
- Chemistry Department, The University, Southampton, U.K
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39
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Hope MJ, Wong KF, Cullis PR. Freeze-fracture of lipids and model membrane systems. JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE 1989; 13:277-87. [PMID: 2681573 DOI: 10.1002/jemt.1060130403] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Model membrane systems are used extensively in all aspects of membrane research, and freeze-fracture is the preeminent procedure for directly visualizing local structure in these lipid dispersions. Here we describe in detail the formation of liposomes and how freeze-fracture is routinely employed as a complementary technique to biophysical and biochemical procedures in the characterization of multilamellar vesicles (most commonly known as liposomes) and unilamellar vesicles. Many preparative procedures exist for the formation of multi- and unilamellar vesicles. Examples of each system are given and their properties as well as freeze-fracture morphology are discussed. The detection of lipid-phase transitions is considered, in particular, with emphasis on the application of freeze-fracture to the study of lipid polymorphism. We briefly discuss the fracturing of apolar lipids which do not adopt bilayer structures but which can be stabilized into microemulsions by a phospholipid monolayer. Finally, a critical assessment is made of filipin as a morphological marker for cholesterol domains in the plane of the bilayer.
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Affiliation(s)
- M J Hope
- Canadian Liposome Co., Ltd., North Vancouver, British Columbia
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40
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Chang MC, Roots BI. The lipid composition of mitochondrial outer and inner membranes from the brains of goldfish acclimated at 5 and 30°C. J Therm Biol 1989. [DOI: 10.1016/0306-4565(89)90005-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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41
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Epand RM, Bottega R. Determination of the phase behaviour of phosphatidylethanolamine admixed with other lipids and the effects of calcium chloride: implications for protein kinase C regulation. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 944:144-54. [PMID: 3179286 DOI: 10.1016/0005-2736(88)90427-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The phase behaviour of 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE) was studied by differential scanning calorimetry and 31P-NMR spectroscopy. Modulation of the phase behaviour of POPE by 1-palmitoyl-2-oleoylphosphatidylserine (POPS). 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), 1,2-di-olein (DOG), CaCl2, MgCl2, and combinations of these substances was studied. The bilayer-forming lipids, POPS and POPC, raise the bilayer-to-hexagonal phase-transition temperature of POPE. The POPC has a greater effect than POPS, probably because the former lipid is more miscible with POPE. Addition of 10 mM CaCl2 has little effect on the phase-transitions of POPE/POPC mixtures, but it greatly decreases the effectiveness of POPS in raising the bilayer-to-hexagonal phase-transition temperature of POPE. The effectiveness of DOG in lowering the phase-transition temperature of POPE is also greatly reduced in the presence of 10 mM CaCl2. This phenomenon may play a role in the negative feedback regulation of protein kinase C.
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Affiliation(s)
- R M Epand
- Department of Biochemistry, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada
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Janoff AS, Kurtz CL, Jablonski RL, Minchey SR, Boni LT, Gruner SM, Cullis PR, Mayer LD, Hope MJ. Characterization of cholesterol hemisuccinate and alpha-tocopherol hemisuccinate vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 941:165-75. [PMID: 2838079 DOI: 10.1016/0005-2736(88)90177-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cholesterol hemisuccinate (CHS) and alpha-tocopherol hemisuccinate (alpha-THS) were found to be capable of forming liposomes of multi- or single lamellar character. Such vesicles formed spontaneously, did not require the use of organic solvents and yielded high trapping efficiencies and captured volumes. Both CHS and alpha-THS systems greatly restricted the motion of intercalated spin labelled fatty acids, yet were more osmotically responsive than similar vesicle types comprised of phosphatidylcholine. Small angle X-ray diffraction measurements were consistent with vesicles possessing extremely weak interlamellar forces. CHS vesicles were found to remain intact in vivo, yet followed a pattern of distribution dissimilar to phosphatidylcholine vesicles.
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Affiliation(s)
- A S Janoff
- Liposome Company, Inc., Princeton, NJ 08540
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Eklund KK, Vuorinen J, Mikkola J, Virtanen JA, Kinnunen PK. Ca2+-induced lateral phase separation in phosphatidic acid/phosphatidylcholine monolayers as revealed by fluorescence microscopy. Biochemistry 1988; 27:3433-7. [PMID: 3390443 DOI: 10.1021/bi00409a046] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Phase separation in mixed monolayers of phosphatidylcholine (PC) and pyrene-labeled phosphatidic acid (PA) was observed by fluorescence microscopy on an air/water interface as a function of subphase Ca2+ concentration and lateral packing pressure of the film. Below 45 mN m-1 and in the absence of Ca2+ no indications of phase immiscibility were observed. Addition of 1 mM Ca2+ caused extensive phase separation, which was evident immediately after spreading of the film. Further increase in Ca2+ concentration up to 30 mM increased the pyrene excimer intensity of the separated phosphatidic acid enriched domains. In the presence of Ca2+ (1-30 mM) and at surface pressures below 10 mN m-1 phase separation was always evident. However, as surface pressure exceeded 10 mN m-1, mixing of PC and PA occurred. Upon decompression of the film, phase separation reappeared at surface pressures close to 10 mN m-1. The surface textures of the film before and after the compression and subsequent relaxation were different. Inclusion of 30 mol% cholesterol increased the number and decreased the size of the PA domains. In films containing 50 mol% cholesterol no phase separation could be detected at the resolution available.
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Affiliation(s)
- K K Eklund
- Department of Membrane Physics, KSV Research Laboratories, Helsinki, Finland
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Boughriet A, Ladjadj M, Bicknell-Brown E. Calcium-induced condensation-reorganization phenomena in multilamellar vesicles of phosphatidic acid. pH potentiometric and 31P-NMR, Raman and ESR spectroscopic studies. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 939:523-32. [PMID: 2833311 DOI: 10.1016/0005-2736(88)90099-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In biological membranes, the anionic characteristics of the polar headgroup of phosphatidic acids are responsible for structural changes induced by Ca2+ in many cellular processes. The very simple headgroup structure of dipalmitoylphosphatidic acid (DPPA) offers particular advantages as a model to study the interactions between Ca2+ and natural phosphatidic acids such as cardiolipin and phosphatidylserine. The effects of calcium ions on DPPA membranes have been studied as a function of temperature by potentiometry and by Raman, ESR and 31P-NMR spectroscopies. The protons in monosodic DPPA liposomes have been considered as a probe to detect pH variations resulting from introduction of Ca2+ inside the membrane. This method has also allowed us to determine the stoichiometry of this reaction: 2 DPPA(H) + Ca2+----Ca(DPPA)2 + 2H+. 31P-NMR spectroscopy has been used to detect reorganization-condensation phenomena in multilamellar vesicles of DPPA under the influence of calcium and temperature. Furthermore, the temperature profiles obtained from Raman spectra for Ca(DPPA)2 membranes provide conclusive evidence that Ca2+ induces major reorganization of the phosphatidic acid component into a highly ordered phase. Quantitative estimates of the degree of motional restriction of spin-labeled soaps embedded inside membranes composed of DPPA with or without Ca2+ have been made using ESR technique. These results are discussed and compared to those found previously for a natural phosphatidic acids such as phosphatidylserine.
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Affiliation(s)
- A Boughriet
- Department of Chemistry, Wayne State University, Detroit, MI
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Webb MS, Tilcock C, Green B. Salt-mediated interactions between vesicles of the thylakoid lipid digalactosyldiacylglycerol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1988. [DOI: 10.1016/0005-2736(88)90130-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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46
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Nayar R, Tilcock CP, Hope MJ, Cullis PR, Schroit AJ. N-succinyldioleoylphosphatidylethanolamine: structural preferences in pure and mixed model membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 937:31-41. [PMID: 3334845 DOI: 10.1016/0005-2736(88)90224-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The structural preferences of the pH-sensitive phospholipid, N-succinyldioleoylphosphatidylethanolamine (N-succinyl-DOPE), have been examined alone and in mixtures with DOPE by 31P-NMR, fluorescence energy transfer, and freeze-fracture techniques. The basic polymorphic behavior of pure N-succinyl-DOPE and DOPE/N-succinyl-DOPE lipid systems and the influence of calcium and pH were investigated. It is shown that, similar to other negatively charged acidic phospholipids, N-succinyl-DOPE adopts the bilayer organization upon hydration. This structure is maintained at both pH 7.4 and 4.0 in the presence or absence of calcium. In the mixed lipid system, N-succinyl-DOPE can stabilize the non-bilayer lipid, DOPE, into a bilayer structure at both pH 7.4 and 4.0 at more than 10 mol% N-succinyl-DOPE, although a narrow 31P-NMR lineshape is observed at acidic pH values. This corresponds to the presence of smaller vesicles as shown by quasi-elastic light scattering measurements. Addition of equimolar calcium (with respect to N-succinyl-DOPE) to the DOPE/N-succinyl-DOPE systems induces the hexagonal HII phase at both pH values. In unilamellar systems with similar lipid composition the addition of Ca2+ results in membrane fusion as indicated by fluorescence energy-transfer experiments. These findings are discussed with regard to the molecular mechanism of the bilayer to hexagonal HII phase transition and membrane fusion and the utility of N-succinyl-DOPE containing pH-sensitive vesicles as drug-delivery vehicles.
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Affiliation(s)
- R Nayar
- Department of Cell Biology, University of Texas M.D. Anderson Hospital and Tumor Institute at Houston 77030
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Stamatotos L, Silvius JR. Effects of cholesterol on the divalent cation-mediated interactions of vesicles containing amino and choline phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 905:81-90. [PMID: 3676317 DOI: 10.1016/0005-2736(87)90011-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We have used assays of lipid probe mixing, contents mixing and contents leakage to monitor the divalent cation-mediated interactions between lipid vesicles containing phosphatidylserine (PS) as a minority component together with mixtures of phosphatidylethanolamine (PE), phosphatidylcholine (PC) or sphingomyelin, and cholesterol in varying proportions. The initial rates of calcium- and magnesium-induced lipid probe quenching between vesicles, which reflect primarily the rates of vesicle aggregation, are strongly reduced as progressively higher proportions of PC or sphingomyelin are incorporated into PE/PS vesicles. The initial rates of divalent cation-induced contents mixing and contents leakage for PE/PS vesicles are also strongly reduced when choline phospholipids are incorporated into the vesicles in even low molar proportions. Sphingomyelin has a more potent inhibitory effect on these processes than does PC at an equal level in the vesicle membranes. The inclusion of cholesterol in these vesicles, at levels up to 1:2 moles sterol/mole phospholipid, has little effect on the rates of calcium- or magnesium-induced vesicle aggregation. However, cholesterol significantly enhances the initial rates of vesicle contents mixing and contents leakage in the presence of divalent cations when the vesicles contain choline as well as amino phospholipids. This effect is substantial only when the level of cholesterol exceeds the level of choline phospholipids in the vesicles. These results may have significance for the fusion of certain cellular membranes in mammalian cells, whose cytoplasmic faces have lipid compositions very similar to those of the vesicles examined in this study.
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Affiliation(s)
- L Stamatotos
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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Boggs JM. Lipid intermolecular hydrogen bonding: influence on structural organization and membrane function. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 906:353-404. [PMID: 3307919 DOI: 10.1016/0304-4157(87)90017-7] [Citation(s) in RCA: 566] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The great variety of different lipids in membranes, with modifications to the hydrocarbon chains, polar groups and backbone structure suggests that many of these lipids may have unique roles in membrane structure and function. Acidic groups on lipids are clearly important, since they allow interaction with basic groups on proteins and with divalent cations. Another important property of certain lipids is their ability to interact intermolecularly with other lipids via hydrogen bonds. This interaction occurs through acidic and basic moieties in the polar head groups of phospholipids, and the amide moiety and hydroxyl groups on the acyl chain, sphingosine base and sugar groups of sphingo- and glycolipids. The putative ability of different classes of lipids to interact by intermolecular hydrogen bonding, the molecular groups which may participate and the effect of these interactions on some of their physical properties are summarized in Table IX. It is frequently questioned whether intermolecular hydrogen bonding could occur between lipids in the presence of water. Correlations of their properties with their molecular structures, however, suggest that it can. Participation in intermolecular hydrogen bonding increases the lipid phase transition temperature by approx. 8-16 Cdeg relative to the electrostatically shielded state and by 20-30 Cdeg relative to the repulsively charged state, while having variable effects on the enthalpy. It increases the packing density in monolayers, possibly also in the liquid-crystalline phase in bilayers, and decreases the lipid hydration. These effects can probably be accounted for by transient, fluctuating hydrogen bonds involving only a small percentage of the lipid at any one time. Thus, rotational and lateral diffusion of the lipids may take place but at a slower rate, and the lateral expansion is limited. Intermolecular hydrogen bonding between lipids in bilayers may be significantly stabilized, despite the presence of water, by the fact that the lipids are already intermolecularly associated as a result of the hydrophobic effect and the Van der Waals' interactions between their chains. The tendency of certain lipids to self-associate, their asymmetric distribution in SUVs, their preferential association with cholesterol in non-cocrystallizing mixtures, their temperature-induced transitions to the hexagonal phase and their inhibitory effect on penetration of hydrophobic residues of proteins partway into the bilayer can all be explained by their participation in intermolecular hydrogen bonding interactions.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J M Boggs
- Department of Biochemistry, Hospital for Sick Children, Toronto, Canada
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49
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Abstract
The phase behavior of phospholipids may be monitored using 31P or 2H NMR techniques, which provide information concerning the motional properties of the lipid ensemble, which may then be correlated with structure. The lamellar/nonlamellar phase preferences of many lipids, either synthetic or naturally derived, may be controlled by factors such as variation in temperature, hydration, or of greater physiological relevance, pH, ionic strength, the presence of divalent cations such as calcium, or the presence of lipid soluble agents as anesthetics and alcohols. The ability of short-chain alcohols to stabilize a bilayer structure for egg PE may be rationalized in terms of the packing of lipids whose dynamic shapes are complementary, as illustrated in Figure 11. On the basis, short-chain alcohols would partition preferentially at the membrane/water interface and would thereby stabilize a lamellar structure. Larger-chain alcohols may partition deeper into the hydrophobic acyl chain region in order to minimize hydrocarbon/water contact and so may perturb the acyl chain packing, increasing the effective swept volume of the chains and so promoting hexagonal HII phase formation.
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Florine KI, Feigenson GW. Influence of the calcium-induced gel phase on the behavior of small molecules in phosphatidylserine and phosphatidylserine-phosphatidylcholine multilamellar vesicles. Biochemistry 1987; 26:1757-68. [PMID: 3036210 DOI: 10.1021/bi00380a039] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The behavior of fluorescent and spin-label probes is examined in several fluid and gel phospholipid phases, with particular focus on the Ca2+-induced gel phase in phosphatidylserine (PS). These probes have behavior characteristic of the type of probe and of the type of lipid environment. Anthroyloxy- and doxyl-labeled PS [12-AS-PS and (7,6)PS, respectively] exhibit greatly restricted and/or slow probe motion in Ca(PS)2, even compared to thermotropic gel-phase lipid at the same temperature. In contrast, anthroyloxy- and doxyl-labeled phosphatidylcholine (PC), as well as fluorescent-labeled and spin-labeled fatty acid derivatives, show no apparent change in probe motion in Ca(PS)2 compared to fluid lamellar lipid. Doxyl-labeled phosphatidic acid, phosphatidylethanolamine, and phosphatidylglycerol show restricted motion in Ca(PS)2 relative to fluid-phase lipid, but the electron paramagnetic resonance (EPR) spectra could not be interpreted in terms of simple models for probe ordering. The fluorescent probes diphenylhexatriene (DPH) and trans-parinaric acid methyl ester (tPNA-Me) show motional behavior in Ca(PS)2 that is intermediate between that observed in fluid and in thermotropic gel-phase lipid. When Ca(PS)2 and fluid PS/PC phases coexist, probe molecules distribute between the two phases. Experiments using fluorescence quenching by spin-labeled PC in PS/PC in excess Ca2+ yield the distribution of several fluorophore probes between fluid liquid-crystal and Ca(PS)2 gel phases, expressed as a concentration ratio, RLC/G. The value of RLC/G = 100 in favor of the fluid phase is obtained for 12-AS-PC, 18 for 12-AS-Me, 12 for DPH, 3 for tPnA-Me, and 1 for 12-AS-PS.(ABSTRACT TRUNCATED AT 250 WORDS)
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