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Du N, Song R, Li H, Song S, Zhang R, Hou W. A Nonconventional Model of Protocell-like Vesicles: Anionic Clay Surface-Mediated Formation from a Single-Tailed Amphiphile. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12579-12586. [PMID: 26524569 DOI: 10.1021/acs.langmuir.5b03477] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report a novel model system of precursor cellular membranes, self-assembled from micellar solution of a common anionic single-tailed amphiphile (STA), including sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS). The self-assembly process was mediated with solid surfaces of Mg2Al-CO3 hydrotalcite-like compound (HTlc), an anionic clay, in the absence of cosurfactants or any additives. The resultant STA vesicles were characterized using negative-staining and cryogenic transmission electron microscopies, as well as dynamic light scattering and steady state fluorescence techniques. Interestingly, the obtained STA vesicles displayed good stability even after the removal of the anionic clay surface (ACS), and a self-reproduction phenomenon was observed for the "preformed" STA vesicles when mixing with corresponding STA micellar solutions. More importantly, the micelle-to-vesicle transition for SDS could be still arisen in high-salinity artificial seawater under the ACS mediation. Instead of conventional fatty acid scenario, our finding provides another novel possible model for protocell-like vesicles, which are easily formed under the plausible prebiotic conditions.
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Affiliation(s)
- Na Du
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
| | - Ruiying Song
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
| | - Haiping Li
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
| | - Shue Song
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
| | - Renjie Zhang
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
| | - Wanguo Hou
- Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University , Jinan 250100, P.R. China
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2
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Nakatani Y, Ribeiro N, Streiff S, Gotoh M, Pozzi G, Désaubry L, Milon A. Search for the most 'primitive' membranes and their reinforcers: a review of the polyprenyl phosphates theory. ORIGINS LIFE EVOL B 2014; 44:197-208. [PMID: 25351682 PMCID: PMC4669544 DOI: 10.1007/s11084-014-9365-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 09/17/2014] [Indexed: 11/26/2022]
Abstract
Terpenoids have an essential function in present-day cellular membranes, either as membrane reinforcers in Eucarya and Bacteria or as principal membrane constituents in Archaea. We have shown that some terpenoids, such as cholesterol and α, ω-dipolar carotenoids reinforce lipid membranes by measuring the water permeability of unilamellar vesicles. It was possible to arrange the known membrane terpenoids in a ‘phylogenetic’ sequence, and a retrograde analysis led us to conceive that single-chain polyprenyl phosphates might have been ‘primitive’ membrane constituents. By using an optical microscopy, we have observed that polyprenyl phosphates containing 15 to 30 C-atoms form giant vesicles in water in a wide pH range. The addition of 10 % molar of some polyprenols to polyprenyl phosphate vesicles have been shown to reduce the water permeability of membranes even more efficiently than the equimolecular addition of cholesterol. A ‘prebiotic’ synthesis of C10 and C15 prenols from C5 monoprenols was achieved in the presence of a montmorillonite clay. Hypothetical pathway from C1 or C2 units to ‘primitive’ membranes and that from ‘primitive’ membranes to archaeal lipids are presented.
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Affiliation(s)
- Yoichi Nakatani
- Institute of Chemistry, University of Strasbourg - CNRS, 67000, Strasbourg, France,
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3
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Georgiou CD, Deamer DW. Lipids as universal biomarkers of extraterrestrial life. ASTROBIOLOGY 2014; 14:541-9. [PMID: 24735484 DOI: 10.1089/ast.2013.1134] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In 1965, James Lovelock published a general statement, based on thermodynamic chemical equilibrium principles, about how to detect extant or extinct life on a planet other than Earth. Nearly 50 years later, it is possible to make such measurements with robotic missions such as current and future Mars rovers, and probes to sample icy plumes of Enceladus or Europa. We make a specific recommendation that certain characteristic patterns in the composition of lipid hydrocarbons can only result from a biological process, because the signal arises from a universal requirement related to lipid bilayer fluidity and membrane stability. Furthermore, the pattern can be preserved over millions of years, and instrumentation is already available to be incorporated into flight missions.
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4
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Ruiz-Mirazo K, Briones C, de la Escosura A. Prebiotic Systems Chemistry: New Perspectives for the Origins of Life. Chem Rev 2013; 114:285-366. [DOI: 10.1021/cr2004844] [Citation(s) in RCA: 563] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kepa Ruiz-Mirazo
- Biophysics
Unit (CSIC-UPV/EHU), Leioa, and Department of Logic and Philosophy
of Science, University of the Basque Country, Avenida de Tolosa 70, 20080 Donostia−San Sebastián, Spain
| | - Carlos Briones
- Department
of Molecular Evolution, Centro de Astrobiología (CSIC−INTA, associated to the NASA Astrobiology Institute), Carretera de Ajalvir, Km 4, 28850 Torrejón de Ardoz, Madrid, Spain
| | - Andrés de la Escosura
- Organic
Chemistry Department, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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5
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Toxvaerd S. The role of carbohydrates at the origin of homochirality in biosystems. ORIGINS LIFE EVOL B 2013; 43:391-409. [PMID: 23996458 DOI: 10.1007/s11084-013-9342-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 07/12/2013] [Indexed: 01/18/2023]
Abstract
Pasteur has demonstrated that the chiral components in a racemic mixture can separate in homochiral crystals. But with a strong chiral discrimination the chiral components in a concentrated mixture can also phase separate into homochiral fluid domains, and the isomerization kinetics can then perform a symmetry breaking into one thermodynamical stable homochiral system. Glyceraldehyde has a sufficient chiral discrimination to perform such a symmetry breaking. The requirement of a high concentration of the chiral reactant(s) in an aqueous solution in order to perform and maintain homochirality; the appearance of phosphorylation of almost all carbohydrates in the central machinery of life; the basic ideas that the biochemistry and the glycolysis and gluconeogenesis contain the trace of the biochemical evolution, all point in the direction of that homochirality was obtained just after- or at a phosphorylation of the very first products of the formose reaction, at high concentrations of the reactants in phosphate rich compartments in submarine hydrothermal vents. A racemic solution of D,L-glyceraldehyde-3-phosphate could be the template for obtaining homochiral D-glyceraldehyde-3-phosphate(aq) as well as L-amino acids.
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Affiliation(s)
- Søren Toxvaerd
- DNRF centre "Glass and Time", IMFUFA, Department of Sciences, Roskilde University, Postbox 260, 4000, Roskilde, Denmark,
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6
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Westall F, Loizeau D, Foucher F, Bost N, Betrand M, Vago J, Kminek G. Habitability on Mars from a microbial point of view. ASTROBIOLOGY 2013; 13:887-97. [PMID: 24015806 DOI: 10.1089/ast.2013.1000] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Extraterrestrial habitability is a complex notion. We briefly review what is known about the origin of life on Earth, that is, life based on carbon chemistry and water. We then discuss habitable conditions (past and present) for established life and for the survival of microorganisms. Based on these elements, we propose to use the term habitable only for conditions necessary for the origin of life, the proliferation of life, and the survival of life. Not covered by this term would be conditions necessary for prebiotic chemistry and conditions that would allow the recognition of extinct or hibernating life. Finally, we apply this concept to the potential emergence of life on Mars where suitable conditions for life to start, proliferate, and survive have been heterogeneous throughout its history. These considerations have a profound impact on the nature and distribution of eventual traces of martian life, or any precursor, and must therefore inform our search-for-life strategies.
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Affiliation(s)
- Frances Westall
- 1 CNRS-OSUC-Centre de Biophysique Moléculaire , Orléans, France
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7
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Nakatani Y, Ribeiro N, Streiff S, Désaubry L, Ourisson G. Search for the most primitive membranes: some remaining problems. ORIGINS LIFE EVOL B 2012; 42:497-501. [PMID: 23080009 DOI: 10.1007/s11084-012-9313-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
Affiliation(s)
- Yoichi Nakatani
- Institut de Chimie, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg, France.
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8
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Ariga K, Hill JP. Monolayers at air-water interfaces: from origins-of-life to nanotechnology. CHEM REC 2011; 11:199-211. [DOI: 10.1002/tcr.201100004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Indexed: 01/06/2023]
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9
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Stadler AM, Harrowfield J. Places and chemistry: Strasbourg—a chemical crucible seen through historical personalities. Chem Soc Rev 2011; 40:2061-108. [DOI: 10.1039/c0cs00197j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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de Anna P, Di Patti F, Fanelli D, McKane AJ, Dauxois T. Spatial model of autocatalytic reactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:056110. [PMID: 20866300 DOI: 10.1103/physreve.81.056110] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Indexed: 05/29/2023]
Abstract
Biological cells with all of their surface structure and complex interior stripped away are essentially vesicles--membranes composed of lipid bilayers which form closed sacs. Vesicles are thought to be relevant as models of primitive protocells, and they could have provided the ideal environment for prebiotic reactions to occur. In this paper, we investigate the stochastic dynamics of a set of autocatalytic reactions, within a spatially bounded domain, so as to mimic a primordial cell. The discreteness of the constituents of the autocatalytic reactions gives rise to large sustained oscillations even when the number of constituents is quite large. These oscillations are spatiotemporal in nature, unlike those found in previous studies, which consisted only of temporal oscillations. We speculate that these oscillations may have a role in seeding membrane instabilities which lead to vesicle division. In this way synchronization could be achieved between protocell growth and the reproduction rate of the constituents (the protogenetic material) in simple protocells.
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Affiliation(s)
- Pietro de Anna
- Géosciences Rennes, UMR 6118, CNRS, Université de Rennes 1, Rennes, France
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11
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Ariga K, Lee MV, Labuta J, Okamoto K, Hill JP. Studies on Langmuir monolayers of polyprenyl phosphates towards a possible scenario for origin of life. Colloids Surf B Biointerfaces 2009; 74:426-35. [DOI: 10.1016/j.colsurfb.2009.07.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 07/21/2009] [Accepted: 07/24/2009] [Indexed: 11/26/2022]
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12
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Laiterä T, Lehto K. Protein-mediated selective enclosure of early replicators inside of membranous vesicles: first step towards cell membranes. ORIGINS LIFE EVOL B 2009; 39:545-58. [PMID: 19609711 DOI: 10.1007/s11084-009-9171-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 06/16/2009] [Indexed: 11/25/2022]
Abstract
Containment in cell membranes is essential for all contemporary life, and apparently even the earliest life forms had to be somehow contained. It has been postulated that random enclosure of replicating molecules inside of spontaneously assembled vesicles would have formed the initial cellular ancestors. However, completely random re-formation or division of such primitive vesicles would have abolished the heritability of their contents, nullifying any selective advantage to them. We propose that the containment of the early replicators in membranous vesicles was adopted only after the invention of genetically encoded proteins, and that selective enclosure of target molecules was mediated by specific proteins. A similar containment process is still utilised by various RNA- and retroviruses to isolate their replication complexes from the host's intracellular environment. Such selective encapsulation would have protected the replicators against competitor and parasitic sequences, and provided a strong positive selection within the replicator communities.
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Affiliation(s)
- Tiina Laiterä
- Laboratory of Plant Physiology and Molecular Biology, University of Turku, Finland
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13
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Fanelli D, McKane AJ. Thermodynamics of vesicle growth and instability. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:051406. [PMID: 19113129 DOI: 10.1103/physreve.78.051406] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Indexed: 05/27/2023]
Abstract
We describe the growth of vesicles, due to the accretion of lipid molecules to their surface, in terms of linear irreversible thermodynamics. Our treatment differs from those previously put forward by consistently including the energy of the membrane in the thermodynamic description. We calculate the critical radius at which the spherical vesicle becomes unstable to a change of shape in terms of the parameters of the model. The analysis is carried out for the case both when the increase in volume is due to the absorption of water and when a solute is also absorbed through the walls of the vesicle.
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Affiliation(s)
- Duccio Fanelli
- Dipartimento di Energetica, Via S. Marta 3, 50139 Florence, Italy
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14
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Gotoh M, Sugawara A, Akiyoshi K, Matsumoto I, Ourisson G, Nakatani Y. Possible molecular evolution of biomembranes: from single-chain to double-chain lipids. Chem Biodivers 2007; 4:837-48. [PMID: 17510999 DOI: 10.1002/cbdv.200790071] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We have studied a possible evolution process permitting a 'primitive' membrane to evolve towards a membrane structure with an outer wall, similar to that of bacteria. We have investigated whether a polysaccharide bearing hydrophobic phytyl or cholesteryl chains coats giant vesicles made of single- or double-chain lipids. Phytyl-pullulan 5b was found to bind to the surface of vesicles made of either single- or double-chain lipids. In contrast, cholesteryl-pullulan 5a only coated the surface of vesicles made of double-chain lipids. These results indicate that there must be a close match between the size and shape of membrane constituents and the hydrophobic molecules to be inserted. This process could, thus, provide a selection mechanism of lipid-membrane constituents during the course of biomembrane evolution. The presence of the above 'hydrophobized' polysaccharides on the surface of different giant vesicles was identified by lectin binding. Both concanavalin A and annexin V were shown by fluorescence microscopy to bind spontaneously to vesicles made of double-chain lipids. Our experiments exemplify that self-organization of amphiphiles into closed vesicles in aqueous solution automatically leads to the coating of vesicles by 'hydrophobized' polysaccharides, which then permit lectin binding. This is a possible mechanism for the evolution of primitive membranes towards 'proto-cells'.
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Affiliation(s)
- Mari Gotoh
- Centre de Neurochimie, 5 rue Blaise Pascal, 67084 Strasbourg, France
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15
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Thomas JA, Rana FR. The influence of environmental conditions, lipid composition, and phase behavior on the origin of cell membranes. ORIGINS LIFE EVOL B 2007; 37:267-85. [PMID: 17361322 DOI: 10.1007/s11084-007-9065-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Accepted: 01/13/2007] [Indexed: 10/23/2022]
Abstract
At some point in life's development, membranes formed, providing barriers between the environment and the interior of the 'cell.' This paper evaluates the research to date on the prebiotic origin of cell membranes and highlights possible areas of continuing study. A careful review of the literature uncovered unexpected factors that influence membrane evolution. The major stages in primitive membrane formation and the transition to contemporary cell membranes appear to require an exacting relationship between environmental conditions and amphiphile composition and phase behavior. Also, environmental and compositional requirements for individual stages are in some instances incompatible with one another, potentially stultifying the pathway to contemporary membranes. Previous studies in membrane evolution have noted the effects composition and environment have on membrane formation but the crucial dependence and interdependence on these two factors has not been emphasized. This review makes clear the need to focus future investigations away from proof-of-principle studies towards developing a better understanding of the roles that environmental factors and lipid composition and polymorphic phase behavior played in the origin and evolution of cell membranes.
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Affiliation(s)
- Jacquelyn A Thomas
- Department of Chemistry, Southwestern College, 900 Otay Lakes Road, Chula Vista, CA, 91910, USA.
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16
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Ariga K, Yuki H, Kikuchi JI, Dannemuller O, Albrecht-Gary AM, Nakatani Y, Ourisson G. Monolayer studies of single-chain polyprenyl phosphates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:4578-83. [PMID: 16032875 DOI: 10.1021/la0467887] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The monolayer properties of some single-chain polyprenyl phosphates (phytanyl, phytyl, and geranylgeranyl phosphates), which we regard as hypothetical primitive membrane lipids, were investigated at the air-water interface by surface pressure-area (pi-A) isotherm measurements. The molecular area/ pressure at various pH conditions dependence revealed the acid dissociation constants (pKa values) of the phosphate. The pKa values thus obtained at the air-water interface (pKa1 = 7.1 and pKa2 = 9.4 for phytanyl phosphate) were significantly shifted to higher pH than those observed in the bilayer state in water (pKa1 = 2.9 and pKa2 = 7.8). The difference in pKa values leads to a stability of the phosphate as both monolayer and bilayer states in a pH range of 2-6. In addition, the presence of ions such as sodium, magnesium, calcium, and lanthanum in the subphase significantly altered the stability of the polyprenyl phosphate monolayers, as shown by the determination of monolayer collapse and compression/expansion hysteresis. Although sodium ions in the subphase showed only a weak effect on the stabilization of the monolayer, addition of magnesium ions or of a small amount of calcium ions significantly suppressed the dissolution of the monolayer into the subphase and increased its mechanical stability against collapse. In contrast, the presence of larger amounts of calcium or of lanthanum ions induced collapse of the monolayers. Based on these experimental facts, a plausible scenario for the formation of primitive cell membrane by transformation of a monolayer to vesicle structures is proposed.
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Affiliation(s)
- Katsuhiko Ariga
- Supermolecules Group, Advanced Materials Laboratory, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan.
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17
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Bombelli C, Borocci S, Lupi F, Mancini G, Mannina L, Segre AL, Viel S. Chiral recognition of dipeptides in a biomembrane model. J Am Chem Soc 2005; 126:13354-62. [PMID: 15479092 DOI: 10.1021/ja0470057] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chiral recognition of the enantiomeric couples of ditryptophan and diphenylalanine was observed by (1)H NMR spectroscopy in micelles formed by sodium N-dodecanoyl-L-prolinate. Ditryptophan showed a selective association with the Z domains of the amidic aggregates, whereas diphenylalanine did not show any selectivity in the association. Partition coefficients between water and aggregates were evaluated by diffusion NMR experiments. Intramolecular distances of ditryptophan isomers associated with chiral aggregates were obtained by ROESY experiments and were used as constraints in molecular mechanics calculations. From these calculations, information on the conformation of the peptides in the chiral aggregates was obtained.
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Affiliation(s)
- Cecilia Bombelli
- IMC-Sezione Meccanismi di Reazione, CNR, c/o Dipartimento di Chimica, Università La Sapienza, Roma, Italy
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19
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Monnard PA, Deamer DW. Membrane self-assembly processes: steps toward the first cellular life. THE ANATOMICAL RECORD 2002; 268:196-207. [PMID: 12382318 DOI: 10.1002/ar.10154] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review addresses the question of the origin of life, with emphasis on plausible boundary structures that may have initially provided cellular compartmentation. Some form of compartmentation is a necessary prerequisite for maintaining the integrity of interdependent molecular systems that are associated with metabolism, and for permitting variations required for speciation. The fact that lipid-bilayer membranes define boundaries of all contemporary living cells suggests that protocellular compartments were likely to have required similar, self-assembled boundaries. Amphiphiles such as short-chain fatty acids, which were presumably available on the early Earth, can self-assemble into stable vesicles that encapsulate hydrophilic solutes with catalytic activity. Their suspensions in aqueous media have therefore been used to investigate nutrient uptake across simple membranes and encapsulated catalyzed reactions, both of which would be essential processes in protocellular life forms.
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Affiliation(s)
- Pierre-Alain Monnard
- Department of Chemistry and Biochemistry, University of California-Santa Cruz, USA.
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20
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Kim GT, Wenz M, Park JI, Hasserodt J, Janda KD. Polyene substrates with unusual methylation patterns to probe the active sites of three catalytic antibodies. Bioorg Med Chem 2002; 10:1249-62. [PMID: 11886788 DOI: 10.1016/s0968-0896(01)00402-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis of two tetraenes that differ in their methylation pattern from the natural substrate in lanosterol biosynthesis, 2,3-oxidosqualene, and their examination with three catalytic antibodies is described. The design of these novel, linear terpenoid structures was governed by initial results obtained from the characterization of the three catalytic antibodies. These were generated by immunization with a steroidal hapten that mimics multicyclization without the necessity for anti-Markovnikov additions or ring expansions. Such a reaction cascade would represent a more 'primitive' version compared to the oxidosqualene cyclization observed in lanosterol, cycloartenol and beta-amyrin biosynthesis and would not require a tail-to-tail connection of the third and fourth isoprene unit as seen in squalene. The first tetraene design (A) only contains trisubstituted double bonds and hence its synthesis starts from farnesol and tris-norgeraniol. The second tetraene design (B) is considered the more precise match to the inducing hapten that generated the antibody collections by exhibiting one disubstituted double bond and its synthesis utilizes a tris-norgeraniol derivative and a symmetrical bis-allylic alcohol as key building blocks. Chromatographic comparison studies lead to the conclusion that the currently studied antibodies also produce monocyclic products from the two substrates as has been formerly observed with a squalene-derived substrate. In contrast, 2,3-oxidosqualene is not accepted by these catalysts supporting the notion that the current substrates are fully bound by recognition of both terminal functional groups.
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Affiliation(s)
- Geun Tae Kim
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
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21
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Bergström M. Thermodynamics of Unilamellar Vesicles: Influence of Mixing on the Curvature Free Energy of a Vesicle Bilayer. J Colloid Interface Sci 2001; 240:294-306. [PMID: 11446813 DOI: 10.1006/jcis.2001.7624] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The influence of mixing on the curvature free energy of a thermodynamically open, reversibly formed vesicle bilayer is investigated by deriving expressions for the various contributions to the bilayer bending constant k(bi) as functions of the structure of aggregated surfactants as well as the solution state (electrolyte concentration, average composition in the bilayers, etc). k(bi) is shown to be lowered in surfactant mixtures as a result of the fact that a mixed vesicle bilayer that is open in the thermodynamic sense may assume different compositions in the inner and outer monolayers. The net contribution of all terms related to surfactant mixing is to lower k(bi). The magnitude of this reduction increases with increasing asymmetry between the two surfactants with respect to charge number, head group size, and tail length. The reduction of k(bi) due to mixing is most pronounced for mixtures where the surfactant that carries charge or has the highest charge number has the larger head group and the smaller tail. Copyright 2001 Academic Press.
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Affiliation(s)
- Magnus Bergström
- Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Stockholm, SE-100 44, Sweden
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Conde-Frieboes K, Blöchliger E. Synthesis of lipids on the micelle/water interface using inorganic phosphate and an alkene oxide. Biosystems 2001; 61:109-14. [PMID: 11716970 DOI: 10.1016/s0303-2647(01)00156-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Liposomes can be considered as a model for a protocell in the context of the origin of life. These self-organising systems can self-reproduce under certain experimental conditions. Herein we demonstrate the ability of another lipid aggregate, micelles, to catalyse a reaction leading finally to the formation of new lipids. In contrast to other published work, where the lipids are products of a hydrolysis reaction, here the lipids are built up from simple precursors. In addition, we observe a transformation of micelles into liposomes.
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Affiliation(s)
- K Conde-Frieboes
- Institut für Polymere, ETH Zentrum, CH-8092 Zurich, Switzerland.
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23
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Nomura SM, Yoshikawa Y, Yoshikawa K, Dannenmuller O, Chasserot-Golaz S, Ourisson G, Nakatani Y. Towards proto-cells: "primitive" lipid vesicles encapsulating giant DNA and its histone complex. Chembiochem 2001; 2:457-9. [PMID: 11828477 DOI: 10.1002/1439-7633(20010601)2:6<457::aid-cbic457>3.0.co;2-f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- S M Nomura
- Department of Physics, Graduate School of Science, Kyoto University & CREST, 606-8502 Kyoto, Japan
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Prapunpoj P, Yamauchi K, Nishiyama N, Richardson SJ, Schreiber G. Evolution of structure, ontogeny of gene expression, and function of Xenopus laevis transthyretin. Am J Physiol Regul Integr Comp Physiol 2000; 279:R2026-41. [PMID: 11080066 DOI: 10.1152/ajpregu.2000.279.6.r2026] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Xenopus laevis transthyretin (xTTR) cDNA was cloned and sequenced. The derived amino acid sequence was very similar to those of other vertebrate transthyretins (TTR). TTR gene expression was observed during metamorphosis in X. laevis tadpole liver but not in tadpole brain nor adult liver. Recombinant xTTR was synthesized in Pichia pastoris and identified by amino acid sequence, subunit molecular mass, tetramer formation, and binding to retinol-binding protein. Contrary to mammalian xTTRs, the affinity of xTTR was higher for L-triiodothyronine than for L-thyroxine. The regions of the TTR genes coding for the NH(2)-terminal sections of the polypeptide chains of TTR seem to have evolved by stepwise shifts of mRNA splicing sites between exons 1 and 2, resulting in shorter and more hydrophilic NH(2) termini. This may be one molecular mechanism of positive Darwinian evolution. Open reading frames with xTTR-like sequences in the genomes of C. elegans and several microorganisms suggested evolution of the TTR gene from ancestor TTR gene-like "DNA modules." Increasing preference for binding of L-thyroxine over L-triiodothyronine may be associated with evolving tissue-specific regulation of thyroid hormone action by deiodination.
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Affiliation(s)
- P Prapunpoj
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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