Nonequilibrium Phenomena in the Phase Separation of a Two-Component Lipid Bilayer

Almeida, Rodrigo F.M. de; Loura, Luís M. S.; Fedorov, Alexander; Prieto, Manuel

doi:10.1016/s0006-3495(02)75444-1

Cited by 76 publications

(77 citation statements)

References 47 publications

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“…As shown, changes in the energy transfer efficiency for ShB are in full agreement with the theoretical expectation for membrane bidimensional random distribution of donors and acceptors within the same plane (37). The acceptor (t-PnA) is known to be internalized in the membrane (38), and from molecular models a distance of about 12.1 Å to the aqueous interface has been estimated (39). In this way, it can be concluded that tyrosine in ShB is located into the membrane at this depth.…”

Section: R(t) ) R′(t)esupporting

confidence: 83%

Intrinsic Tyrosine Fluorescence as a Tool To Study the Interaction of the Shaker B “Ball” Peptide with Anionic Membranes

et al. 2003

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Steady-state and time-resolved fluorescence from the single tyrosine in the inactivating peptide of the Shaker B potassium channel (ShB peptide) and in a noninactivating peptide mutant, ShB-L7E, has been used to characterize their interaction with anionic phospholipid membranes, a model target mimicking features of the inactivation site on the channel protein. Partition coefficients derived from steady-state anisotropy indicate that both peptides show a high affinity for anionic vesicles, being higher in ShB than in ShB-L7E. Moreover, differential quenching by lipophilic spin-labeled probes and fluorescence energy transfer using trans-parinaric acid as the acceptor confirm that the ShB peptide inserts deep into the membrane, while the ShB-L7E peptide remains near the membrane surface. The rotational mobility of tyrosine in membrane-embedded ShB, examined from the decay of fluorescence anisotropy, can be described by two different rotational correlation times and a residual constant value. The short correlation time corresponds to fast rotation reporting on local tyrosine mobility. The long rotational correlation time and the high residual anisotropy suggest that the ShB peptide diffuses in a viscous and anisotropic medium compatible with the aliphatic region of a lipid bilayer and support the hypothesis that the peptide inserts into it as a monomer, to configure an intramolecular -hairpin structure. Assuming that this hairpin structure behaves like a rigid body, we have estimated its dimensions and rotational dynamics, and a model for the peptide inserted into the bilayer has been proposed.The inactivating Shaker B (ShB) 1 peptide comprises the 20 N-terminal amino acids (H 2 N-MAAVAGLYGLGED-RQHRKKQ) of each subunit in the Shaker B potassium channel, the so-called inactivating "ball", responsible for inducing fast, N-type inactivation in this and many other related or unrelated channels (1-6). Fast inactivation implies the physical occlusion of the channel's cytoplasmic mouth (7), with the ball peptide acting as an open channel blocker. The site on the channel where the ball peptide interacts consists of a hydrophobic protein pocket, separated from the cytoplasm by a region with a negative surface potential (8,9). Such channel domains can be partly mimicked by anionic phospholipid membranes, which also contain a hydrophobic region (the hydrophobic bilayer) and a negatively charged surface. Thus, anionic phospholipid vesicles have been used as model targets to gain insight into the molecular events in which the ShB peptide might be involved during channel inactivation (10-14). Fourier transform IR spectroscopy, differential scanning calorimetry, and steady-state fluorescence studies of fluorophore-labeled ShB peptide suggest that the ShB peptide (a) binds to the vesicle surface with high affinity, (b) readily adopts a strongly hydrogen-bonded intramolecular -hairpin structure, and (c) becomes inserted into the hydrophobic bilayer in a monomeric form. In contrast, a noninactivating mutant peptide ShB-L7E ...

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Section: R(t) ) R′(t)esupporting

confidence: 83%

Intrinsic Tyrosine Fluorescence as a Tool To Study the Interaction of the Shaker B “Ball” Peptide with Anionic Membranes

et al. 2003

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“…The thickness of the lipid film was estimated as reported in the literature [5,27] fixing the real part of the refractive index at 1.5 [29,30]. The very low extinction coefficient values (k) obtained in this work ranged from 0.03 to 0.11, which indicates nearly transparent films, as expected for thin organic layers [27].…”

Section: Ellipsometrysupporting

confidence: 60%

Phospholipid/cholesterol/decanethiol mixtures for direct assembly of immunosensing interfaces

Almeida

Marquês

Liu

et al. 2015

Colloids and Surfaces B: Biointerfaces

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a b s t r a c tIn this work, a simple yet robust method to prepare lipid-based biosensing interfaces on gold using common lipids (a phospholipid and cholesterol) and an alkanethiol is reported. The lipids were carefully chosen to tailor the biophysical properties of the bilayer. The simplicity of the method relies on the incorporation of a small percentage of decanethiol in the lipid vesicles for a direct formation of a thiol-linked supported lipid bilayer, which is advantageous in several respects. It prevents the use of specially synthesized thiolipids and preserves the natural fluidity and dynamics of the lipids. As a consequence the whole arrangement is extremely stable regarding ionic strength changes and solution flow during surface plasmon resonance experiments. Moreover, we show that this interface is very effective on suppressing the nonspecific adsorption of proteins on the surface, and enables the covalent attachment of the recognition antibody. The subsequent detection of specific interaction toward antigen was monitored in real-time by SPR and confirmed by ellipsometric measurements. This lipid-based biosensing platform is versatile and can be adapted to the biorecognition reaction of interest.

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“…[17][18][19] Used as FRET donors, NBD-diC n PE probes form, together with acceptor rhodamine B PE derivatives, a very well-known Förster pair for the studies of membrane organization [20][21][22][23][24] as well as quantification of lipid mixing and exchange. 25 Alternatively, NBD probes can be used as acceptors to chromophores including diphenylhexatriene 26,27 or trans-parinaric acid, 28 or even as donors and acceptors simultaneously in homo-FRET studies. 20 Several fluorescence spectroscopic and microscopic studies have also indicated that, contrary to the vast majority of membrane fluorescent probes, doubly saturated long-chained NBD-diC n PE partitions favourably to liquid ordered (lo) phases in systems displaying lo/liquid disordered phase coexistence, 22,24,29,30 although the phase preference depends both on the probe acyl chain length and the composition of the underlying lipid mixture.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of NBD-head group labelled phosphatidylethanolamines in POPC bilayers: a molecular dynamics study

Filipe

Santos

Ramalho

et al. 2015

Phys. Chem. Chem. Phys.

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A complete homologous series of fluorescent phosphatidylethanolamines (diC n PE), labelled at the head group with a 7-nitrobenz-2-oxa-1,3-diazo-4-yl(NBD) fluorophore and inserted in 1-palmitoyl, 2-oleoyl-snglycero-3-phosphocholine (POPC) bilayers, was studied using atomistic molecular dynamics simulations. The longer-chained derivatives of NBD-diC n PE, with n = 14, 16, and 18, are commercially available, and widely used as fluorescent membrane probes. Properties such as location of atomic groups and acyl chain order parameters of both POPC and NBD-diC n PE, fluorophore orientation and hydrogen bonding, membrane electrostatic potential and lateral diffusion were calculated for all derivatives in the series. Most of these probes induce local disordering of POPC acyl chains, which is on the whole counterbalanced by ordering resulting from binding of sodium ions to lipid carbonyl/glycerol oxygen atoms. An exception is found for NBD-diC 16 PE, which displays optimal matching with POPC acyl chain length and induces a slight local ordering of phospholipid acyl chains. Compared to previously studied fatty amines, acyl chain-labelled phosphatidylcholines, and sterols bearing the same fluorescent tag, the chromophore in NBD-diC n PE locates in a similar region of the membrane (near the glycerol backbone/carbonyl region) but adopts a different orientation (with the NO 2 group facing the interior of the bilayer). This modification leads to an inverted orientation of the P-N axis in the labelled lipid, which affects the interface properties, such as the membrane electrostatic potential and hydrogen bonding to lipid head group atoms. The implications of this study for the interpretation of the photophysical properties of NBD-diC n PE (complex fluorescence emission kinetics, differences with other NBD lipid probes) are discussed.

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Nonequilibrium Phenomena in the Phase Separation of a Two-Component Lipid Bilayer

Cited by 76 publications

References 47 publications

Intrinsic Tyrosine Fluorescence as a Tool To Study the Interaction of the Shaker B “Ball” Peptide with Anionic Membranes

Intrinsic Tyrosine Fluorescence as a Tool To Study the Interaction of the Shaker B “Ball” Peptide with Anionic Membranes

Phospholipid/cholesterol/decanethiol mixtures for direct assembly of immunosensing interfaces

Behaviour of NBD-head group labelled phosphatidylethanolamines in POPC bilayers: a molecular dynamics study

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