The interaction of fluorescent DPH probes with unsaturated phospholipid membranes: A molecular dynamics study

Hurjui, Ion; Neamţu, Andrei; Dorohoi, Dana Ortansa

doi:10.1016/j.molstruc.2012.12.015

Cited by 18 publications

(15 citation statements)

References 40 publications

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“…Fig. 1 shows structures and numbering of relevant atoms of the DPH, TMA-DPH, POPC and cholesterol molecules, while the charges adopted for the probes are displayed in Table 1 (for DPH, the charges agree closely with the previously reported values of Repáková et al [22] and Hurjui et al [24]). Bilayers containing probe molecules (either 1 or 2 in each leaflet) were obtained by random insertion inside the bilayer without replacement of phospholipids or cholesterol, with orientation roughly aligned with the bilayer normal.…”

Section: Methodssupporting

confidence: 80%

“…These observations agree with the results of Repáková et al [22] and Franová et al [15], who found that no distinct correlation between orientation and location existed in fluid DPPC and DPPC/cholesterol bilayers (respectively), and, in particular, orientations with θ~90°were not especially favored near z = 0. More recently, Hurjui et al [24] reported the existence of a significant population of highly tilted DPH molecules located in the ordered upper acyl chain region of DOPC bilayers, just below the lipid ester/carbonyl atoms (z~1.2 nm). Our results show qualitative agreement with this observation, to the extent that our most probable location for highly tilted DPH molecules (z~1.0 nm) is more external than the overall average center of mass location (z~0.7 nm).…”

Section: Location and Conformation Of Dph And Tma-dphmentioning

confidence: 99%

“…A later report by the same group [15] extended this characterization to DPPC/cholesterol mixtures, revealing that the presence of the latter affects the location and orientation of bilayer-inserted DPH slightly, and that for 20 mol% of cholesterol, the well-known ordering effect of this component is so dominant that the additional role of DPH becomes almost negligible. More recently, in a study of DPH in unsaturated DOPC bilayers, a representative population of DPH molecules was intriguingly found in the acyl-chain region of the bilayer immediately beneath the DOPC/water interface, with a tilt angle of near 90°relative to the bilayer normal [24]. No such orientations were found for molecules close to the bilayer center, however.…”

Section: Introductionmentioning

confidence: 99%

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Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study

Canto

Robalo

Santos

et al. 2016

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Fluorescence spectroscopy and microscopy have been utilized as tools in membrane biophysics for decades now. Because phospholipids are non-fluorescent, the use of extrinsic membrane probes in this context is commonplace. Among the latter, 1,6-diphenylhexatriene (DPH) and its trimethylammonium derivative (TMA-DPH) have been extensively used. It is widely believed that, owing to its additional charged group, TMA-DPH is anchored at the lipid/water interface and reports on a bilayer region that is distinct from that of the hydrophobic DPH. In this study, we employ atomistic MD simulations to characterize the behavior of DPH and TMA-DPH in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and POPC/cholesterol (4:1) bilayers. We show that although the dynamics of TMA-DPH in these membranes is noticeably more hindered than that of DPH, the location of the average fluorophore of TMA-DPH is only~3-4 Å more shallow than that of DPH. The hindrance observed in the translational and rotational motions of TMA-DPH compared to DPH is mainly not due to significant differences in depth, but to the favorable electrostatic interactions of the former with electronegative lipid atoms instead. By revealing detailed insights on the behavior of these two probes, our results are useful both in the interpretation of past work and in the planning of future experiments using them as membrane reporters.

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Section: Methodssupporting

confidence: 80%

Section: Location and Conformation Of Dph And Tma-dphmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study

Canto

Robalo

Santos

et al. 2016

Biochimica et Biophysica Acta (BBA) - Biomembranes

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show abstract

“…In fact, the behaviour of DPH has to date only been examined in model membranes containing linear-chain lipids. In these systems, it has been shown to lie either close to the carbonyl region, to spread broadly within the bilayer with its long axis aligned along the acyl chains, or to reside in the centre of bilayers parallel to the bilayer plane 47,48. Therefore, as the localisation and orientation of DPH in lipid bilay-…”

mentioning

confidence: 99%

Effect of Ring Size in ω-Alicyclic Fatty Acids on the Structural and Dynamical Properties Associated with Fluidity in Lipid Bilayers

Poger

Mark

2015

Langmuir

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Fatty acids containing a terminal cyclic group such as cyclohexyl and cycloheptyl are commonly found in prokaryotic membranes, especially in those of thermo-acidophilic bacteria. These so-called ω-alicyclic fatty acids have been proposed to stabilise the membranes of bacteria by reducing the fluidity in membranes and increasing lipid packing and lipid chain order. In this article, molecular dynamics simulations are used to examine the effect of 3-to 7-membered cycloalkyl saturated and unsaturated (cyclopent-2-enyl and phenyl) rings in ω-alicyclic fatty acyl chains on the structure (lipid packing, lipid chain order and fraction of gauche defects in the chains) and dynamics (lateral lipid diffusion) of a model lipid bilayer. It was found that ω-alicyclic chains in which the ring was saturated reduced lipid condensation and lowered chain order which would be associated with enhanced fluidity. However, this effect was limited. The lateral diffusion of the lipids diminished as the ring size increased. In particular, ω-cyclohexyl and ω-cycloheptyl acyl tails led to a decrease in lipid diffusion.In contrast, ω-alicyclic acyl chains that contain an unsaturated ring promoted membrane fluidity both in terms of changes in membrane structure and lipid diffusion. This may indicate that saturated and unsaturated terminal rings in ω-alicyclic fatty acids fulfil alternative functions within membranes. Overall, the simulations suggest that ω-alicyclic fatty acids in which the terminal ring is saturated might protect the membrane of thermo-acidophilic bacteria from high-temperature and low-pH conditions through a "dynamical barrier" that would limit lipid diffusion and transmembrane diffusion of undesired ions and molecules.

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“…The DPH molecules orient loosely between the hydrophobic tails throughout the lipid bilayer and lie parallel to the axis of lipid acyl chains. 49 TMA-DPH is a cationic derivative of DPH and is located near the phospholipid heads at the membrane-water interface. 50 Among all the cases depicted in Figure 4A-D, in comparison with the control SUVs, there is a slight increase in the S values of SUVs treated with SPIONs by both the methods, that is, encapsulation and incubation.…”

mentioning

confidence: 99%

Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

Santhosh

Drašler

Drobne

et al. 2015

IJN

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Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl- sn -glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications.

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The interaction of fluorescent DPH probes with unsaturated phospholipid membranes: A molecular dynamics study

Cited by 18 publications

References 40 publications

Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study

Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study

Effect of Ring Size in ω-Alicyclic Fatty Acids on the Structural and Dynamical Properties Associated with Fluidity in Lipid Bilayers

Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

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