Monitoring changes of paramagnetically-shifted 31P signals in phospholipid vesicles

Joyce, Rebecca E.; Williams, Thomas L.; Serpell, Louise C.; Day, Iain J.

doi:10.1016/j.cplett.2016.02.007

Cited by 4 publications

(14 citation statements)

References 43 publications

(57 reference statements)

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“…Lanthanides have previously been shown to interact with the phospholipid head group region. 6,63 An increased head group mobility would enable a greater number of lanthanide ions to interact. This may have less of an impact on Dy 3+ in comparison to Yb 3+ due to size differences.…”

Section: Resultsmentioning

confidence: 99%

“…In the latter application, lanthanide ions applied externally to extruded phospholipid vesicles are used to distinguish between the signal from the inner and outer lipids of the membrane. 5,6 The difference in signal is attributed to lanthanide induced chemical shifts in the NMR signal from the outer head groups of the vesicle. By monitoring the change in this signal over time the intrinsic rate of lipid flip-flop within a model membrane system can be quantified.…”

Section: Introductionmentioning

confidence: 99%

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How does ytterbium chloride interact with DMPC bilayers? A computational and experimental study

Gonzalez

Barriga

Richens

et al. 2017

Phys. Chem. Chem. Phys.

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Lanthanide salts have been studied for many years, primarily in Nuclear Magnetic Resonance (NMR) experiments of mixed lipid-protein systems and more recently to study lipid flip-flop in model membrane systems. It is well recognised that lanthanide salts can influence the behaviour of both lipid and protein systems, however a full molecular level description of lipid-lanthanide interactions is still outstanding. Here we present a study of lanthanide-bilayer interactions, using molecular dynamics computer simulations, fluorescence electrostatic potential experiments and nuclear magnetic resonance. Computer simulations reveal the microscopic structure of DMPC lipid bilayers in the presence of Yb, and a surprising ability of the membranes to adsorb significant concentrations of Yb without disrupting the overall membrane structure. At concentrations commonly used in NMR experiments, Yb ions bind strongly to 5 lipids, inducing a small decrease of the area per lipid and a slight increase of the ordering of the aliphatic chains and the bilayer thickness. The area compressibility modulus increases by a factor of two, with respect to the free-salt case, showing that Yb ions make the bilayer more rigid. These modifications of the bilayer properties should be taken into account in the interpretation of NMR experiments.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

How does ytterbium chloride interact with DMPC bilayers? A computational and experimental study

Gonzalez

Barriga

Richens

et al. 2017

Phys. Chem. Chem. Phys.

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“…The large increase in the flip-flop rates and activation energies under salt conditions, might be important to rationalise NMR experiments that use ytterbium salts to access the lipid dynamics. 17,19,44 There are several lines of future enquiry stemming from our work. Since we have used a well defined membrane compositions, our results should motivate controlled experiments to verify the conclusions presented in this work.…”

Section: Resultsmentioning

confidence: 97%

“…Such effect would be important to understand the role of salt on membrane biophysics as well as to interpret experimental results obtained with different experimental techniques. [14][15][16][17] In our previous work, 18 we demonstrated that Yb 3+ ions modify significantly the membrane rigidity and the orientation of the lipid head group. The question we wish to address in this work is whether the interactions of physiological relevant cations, Na + , K + , Mg 2+ , Ca 2+ and ions employed in NMR experiments, Yb 3+ , might modify the lipid flip-flop translocation rates.…”

Section: Introductionmentioning

confidence: 91%

“…Given the polar character of the lipid head groups, we expect that the salt composition, the ion charge in particular, might influence the activation energy required for the nucleation of the pores and consequently modify the rate of lipid flip-flop. Such effect would be important to understand the role of salt in membrane biophysics as well as to interpret experimental results obtained with different experimental techniques. − …”

Section: Introductionmentioning

confidence: 99%

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Membrane–Ion Interactions Modify the Lipid Flip-Flop Dynamics of Biological Membranes: A Molecular Dynamics Study

Gonzalez

Bresme

2020

J. Phys. Chem. B

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The asymmetric distribution of lipids in the cell membrane is maintained by protein transporters, and in the absence of proteins, by spontaneous flip-flop of lipids that involve the formation of transient pores in the membrane. The composition of the cell membranes influences the metabolism of the cell by modulating the function of transmembrane proteins, and flip-flop processes are therefore of key importance. Membranes are in direct contact with aqueous solutions, containing ions of different composition that interact with the lipid head groups or cross the cell membrane through transmembrane channels. The impact of the ions on the lipid flip-flop rate is however an outstanding question. Here we show that flip-flop rate slows down significantly with the increasing valence of the cation, from minutes for monovalent cations (Na + , K + ), to hours for divalent (Mg 2+ , Ca 2+ ) or days for trivalent cations (Yb 3+ ).

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Inhibitory Effect of Lanthanides on Native Lipid Flip-Flop

Cheng

Conboy

2022

J. Phys. Chem. B

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The influence of ytterbium ions (Yb3+), a commonly used paramagnetic NMR chemical shift reagent, on the physical properties and flip-flop kinetics of dipalmitoylphosphatidylcholine (DPPC) planar supported lipid bilayers (PSLBs) was investigated. Langmuir isotherm studies revealed that Yb3+ interacts strongly with the phosphate headgroup of DPPC, evidenced by the increases in shear and compression moduli. Using sum-frequency vibrational spectroscopy, changes in the acyl chain ordering and phase transition temperature were also observed, consistent with Yb3+ interacting with the phosphate headgroup of DPPC. The changes in the physical properties of the membrane were also observed to be concentration dependent, with more pronounced modification observed at low (50 μM) Yb3+ concentrations compared to 6.5 mM Tb3+, suggesting a cross-linking mechanism between adjacent DPPC lipids. Additionally, the changes in membrane packing and phase transition temperatures in the presence of Tris buffer suggested that a putative Yb(Tris)3+ complex forms that coordinates to the PC headgroup. The kinetics of DPPC flip-flop in the gel and liquid crystalline (lc) phases were substantially inhibited in the presence of Yb3+, regardless of the Yb3+ concentration. Analysis of the flip-flop kinetics under the framework of transition state theory revealed that the free energy barrier to flip-flop in both the gel and lc phases was substantial increased over a pure DPPC membrane. In the gel phase, the trend in the free energy barrier appeared to follow the trend in the shear moduli, suggesting that the Yb3+–DPPC headgroup interaction was driving the increase in the activation free energy barrier. In the lc phase, activation free energies of DPPC flip-flop in the presence of 50 μM or 6.5 mM Yb3+ were found to mirror the free energies of TEMPO–DPPC flip-flop, leading to the conclusion that the strong interaction between Yb3+ and the PC headgroup was essentially manifested as a headgroup charge modification. These studies illustrate that the presence of the lanthanide Yb3+ results in significant modification to the lipid membrane physical properties and, more importantly, results in a pronounced inhibition of native lipid flip-flop.

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Monitoring changes of paramagnetically-shifted 31P signals in phospholipid vesicles

Cited by 4 publications

References 43 publications

How does ytterbium chloride interact with DMPC bilayers? A computational and experimental study

How does ytterbium chloride interact with DMPC bilayers? A computational and experimental study

Membrane–Ion Interactions Modify the Lipid Flip-Flop Dynamics of Biological Membranes: A Molecular Dynamics Study

Inhibitory Effect of Lanthanides on Native Lipid Flip-Flop

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