Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane

Nelson, Steven C.; Neeley, Steven K; Melonakos, Eric D.; Bell, John D.; Busath, David D.

doi:10.1186/2046-1682-5-5

Cited by 14 publications

(17 citation statements)

References 41 publications

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“…C3 is often found near the bilayer midplane, more so in POPC than in POPC/20 mol% cholesterol. The average location in the former system, (0.34 ± 0.03) nm, actually agrees well with the aforementioned location ((0.28 ± 0.19) nm) of the TMA-DPH end H atom in fluid DPPC, as calculated by Nelson et al [25]. However, we could not confirm the corresponding result obtained by these authors for DPH ((0.42 ± 0.35) nm), which would point to a possibly more external location of this probe.…”

Section: Location and Conformation Of Dph And Tma-dphsupporting

confidence: 89%

“…For each lipid system, the difference between the location of the two probes, though small, was still significant (see error bars in Fig. 2), at variance with the data of Nelson et al [25].…”

Section: Location and Conformation Of Dph And Tma-dphsupporting

confidence: 78%

“…This finding is in line with the work of Franová, Repáková and coworkers [15,23] who found small overall DPH-induced effects on both DPPC and DPPC/20 mol% cholesterol fluid bilayers, including no appreciable changes in the experimentally measured main transition temperature and enthalpy. Indeed, the fact that DPH and TMA-DPH report correctly on phospholipid phase transitions (as verified in numerous historical works, and more recently by Nelson et al in DPPC membranes [25]) agrees with the lack of major disturbance of membrane properties. In comparison, other probes, such as NBD-PC, produce much more pronounced changes, including considerable broadening of DPPC phase transition for probe concentrations similar to those addressed here [80].…”

Section: Structural and Conformational Properties Of The Host Lipidssupporting

confidence: 70%

“…In contrast with DPH, to our knowledge a sole MD study has been reported for TMA-DPH in fluid DPPC [25], only covering 2 ns of simulation (of which 1 ns was taken as system equilibration). The simulations focused in the atomic positions of the end nitrogen and hydrogen atoms, and, for example, revealed no significant differences in the positions of the H atoms closest to the bilayer center for DPH (0.42 ± 0.35 nm relative to the center) and TMA-DPH (0.28 ± 0.19 nm).…”

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: Location and Conformation Of Dph And Tma-dphsupporting

confidence: 89%

Section: Location and Conformation Of Dph And Tma-dphsupporting

confidence: 78%

Section: Structural and Conformational Properties Of The Host Lipidssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

“…32 A and B are constant coefficients for the quadratic baseline. Ignoring the quadratic baseline, eq 2 depicts a sigmoid function with asymptotic end behavior in the limit as T is significantly far from the phase transition region.…”

Section: Methodsmentioning

confidence: 99%

Analysis of Lipid Phase Behavior and Protein Conformational Changes in Nanolipoprotein Particles upon Entrapment in Sol–Gel-Derived Silica

et al. 2014

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The entrapment of nanolipoprotein particles (NLPs) and liposomes in transparent, nanoporous silica gel derived from the precursor tetramethylorthosilicate was investigated. NLPs are discoidal patches of lipid bilayer that are belted by amphiphilic scaffold proteins and have an average thickness of 5 nm. The NLPs in this work had a diameter of roughly 15 nm and utilized membrane scaffold protein (MSP), a genetically altered variant of apolipoprotein A-I. Liposomes have previously been examined inside of silica sol–gels and have been shown to exhibit instability. This is attributed to their size (∼150 nm) and altered structure and constrained lipid dynamics upon entrapment within the nanometer-scale pores (5–50 nm) of the silica gel. By contrast, the dimensional match of NLPs with the intrinsic pore sizes of silica gel opens the possibility for their entrapment without disruption. Here we demonstrate that NLPs are more compatible with the nanometer-scale size of the porous environment by analysis of lipid phase behavior via fluorescence anisotropy and analysis of scaffold protein secondary structure via circular dichroism spectroscopy. Our results showed that the lipid phase behavior of NLPs entrapped inside of silica gel display closer resemblance to its solution behavior, more so than liposomes, and that the MSP in the NLPs maintain the high degree of α-helix secondary structure associated with functional protein–lipid interactions after entrapment. We also examined the effects of residual methanol on lipid phase behavior and the size of NLPs and found that it exerts different influences in solution and in silica gel; unlike in free solution, silica entrapment may be inhibiting NLP size increase and/or aggregation. These findings set precedence for a bioinorganic hybrid nanomaterial that could incorporate functional integral membrane proteins.

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Isoflurane increases cell membrane fluidity significantly at clinical concentrations

Patel

Chowdhury

Noorani

et al. 2020

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane

Cited by 14 publications

References 41 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

Analysis of Lipid Phase Behavior and Protein Conformational Changes in Nanolipoprotein Particles upon Entrapment in Sol–Gel-Derived Silica

Isoflurane increases cell membrane fluidity significantly at clinical concentrations

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