Routes to Functional Vesicle Membranes without Proteins

Fuhrhop, Jürgen‐Hinrich; Mathieu, Joachim

doi:10.1002/anie.198401001

Cited by 152 publications

(63 citation statements)

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“…The bispyridinium compounds synthesized above present structural and physical properties compatible with the requirements for designing molecular wires. Since they possess charged terminal groups separated by a long lipophilic polyene chain they should be suitable for incorporation into lipid membranes, in particular of vesicles, and be able to span the membrane if the chain is long enough to allow the polar head groups to reach into the polar regions on each side of a bilayer or of a monolayer membrane (26). Thus, carotenoids bearing hydroxyl groups at both ends may act as membrane reinforcers by spanning the bilayer (27,28 (Fig.…”

Section: Methodsmentioning

confidence: 99%

Molecular devices: Caroviologens as an approach to molecular wires—synthesis and incorporation into vesicle membranes

Arrhenius

Blanchard‐Desce

Dvolaïtzky

et al. 1986

Proc. Natl. Acad. Sci. U.S.A.

124

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Molecular wires, which would allow electron flow to take place between different components, are important elements in the design of molecular devices. An approach to such species would be molecules possessing an electron-conducting conjugated chain, terminal electroactive polar groups, and a length sufficient to span a lipid membrane. To this end, bispyridinium polyenes of different lengths have been synthesized and their incorporation into the bilayer membrane of sodium dihexadecyl phosphate vesicles has been studied. Since they combine the features of carotenoids and of viologens, they may be termed caroviologens. Vesicles containing the caroviologen whose length approximately corresponds to the thickness of the sodium dihexadecyl phosphate bilayer display temperature-dependent changes of its absorption spectrum reflecting the gel --liquidcrystal phase transition of the membrane. The data agree with a structural model in which the caroviologens of sufficient length span the bilayer membrane, the pyridinium sites being close to the negatively charged outer and inner surfaces of the sodium dihexadecyl phosphate vesicles and the polyene chain crossing the lipidic interior of the membrane. These membranes may now be tested in processes in which the caroviologen would function as a continuous, transmembrane electron channel-i.e., as a molecular wire. Various further developments may be envisaged along these lines.Molecular devices may be defined as structurally organized and functionally integrated chemical systems built into supramolecular architectures. The development of such devices requires the design of molecular components performing a given function (e.g., photoactive, electroactive, ionoactive, thermoactive, or chemoactive) and suitable for assembly into an organized array. A major requirement is that these components and the devices that they build up should perform their function(s) at the molecular and supramolecular (1) levels, as distinct from the level of the bulk material.

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Section: Methodsmentioning

confidence: 99%

Molecular devices: Caroviologens as an approach to molecular wires—synthesis and incorporation into vesicle membranes

Arrhenius

Blanchard‐Desce

Dvolaïtzky

et al. 1986

Proc. Natl. Acad. Sci. U.S.A.

124

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“…[8][9][10] . Our methodology chemically differentiates exo from endo liposomal head groups of functionalized lipids by reactions that preferentially occur at the bilayer's exoliposomal surface.…”

Section: Surface Differentiation Of Liposomesmentioning

confidence: 99%

Dynamics of lipids in synthetic membranes

Moss¹

1994

Pure and Applied Chemistry

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Bilayer coliposomes were created from blends of head-group functionalized and non-functionalized synthetic lipids. Functionalized lipids in the outer leaflets of the bilayers were then chemically differentiated from the (unchanged) functionalized lipids of the inner leaflets, thus permitting study of the dynamics of the ensuing reequilibration that occurred via thermally activated transbilayer lipid migration ("flip-flop'). Our particular focus was the relation between lipid molecular structure and flip-flop dynamics within the bilayer membranes. The structural factors investigated included chain length, unsaturation, cyclopropanation, alkylation, and 'stiffening'. The effects of head group type (ammonium ion or phosphocholine) and overall lipid character (monopolar or bolaamphiphilic) were also examined. The results highlight factors that simultaneously allow both the membrane fluidity and maintenance of leaflet diff erentation that are essential to proper biological function.Synthetic bilayer lipid vesicles or liposomes are of interest in their own right and as models for biological membranes ( ref. 1,2). These closed, hollow spheres or ellipsoids create aqueous reaction loci of different chemical or microenvironmental properties separated by hydrocarbon barriers. Thus the permeation of reagents and ions across these barriers can be controlled, and their reactivity modulated. Moreover, one can chemically differentiate the exoliposomal and endoliposomal surfaces, furthering the analogy to biological membranes, where transverse asymmetry between the exo and endo leaflets of the bilayer is common and functionally significant ( ref. 1-5). With differentiated bilayer surfaces, we can study the dynamics of individual lipid molecules as they undergo reequilibration, and we can relate the dynamics to the lipid's molecular structure.The most common biological lipids are phosphoglycerides, e &~ 1. Kunitake (ref. 6) and O-1 2Fendler (ref. 7) showed that double chain quaternary ammonium ions (2) could also form liposomes, so that one could model bilayer membranes with lipids of the simplest structure. 851

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“…Bolaamphiphiles molecules in which two polar functional headgroups are linked covalently by one or more hydrophobic hydrocarbon chains [1][2][3][4][5][6][7][8][9][10][11]. Gemini amphiphiles are molecules containing two headgroups and two aliphatic chains linked by a rigid or flexible spacer.…”

Section: Introductionmentioning

confidence: 99%