Surface potential of phosphoinositide membranes: Comparison between theory and experiment

Ohki, Shinpei; Müller, Mat­thias; Arnold, Klaus; Ohshima, Hiroyuki

doi:10.1016/j.colsurfb.2010.03.052

Cited by 12 publications

(15 citation statements)

References 42 publications

(71 reference statements)

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“…Furthermore, since fatty acids or phospholipids usually present unsaturations in the hydrocarbon chains, the study of mixtures of saturated and unsaturated compounds is of interest. Recent articles on fatty acid systems with mixed saturated-unsaturated hydrocarbon chains are those of [33,34], and on phospholipids systems with mixed saturated-unsaturated hydrocarbon chains are those of [35][36][37][38][39][40][41][42][43][44]. The main achievements reported in these works will be commented in the discussion section, in connection with the results of the present work.…”

Section: Introductionmentioning

confidence: 64%

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Torrent‐Burgués

2018

Colloids and Interfaces

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Mixed fatty acids or mixed phospholipids systems with saturated-unsaturated hydrocarbon chains are of biological interest. In this work, the monolayers of oleic acid-stearic acid (OA-SA) and palmitoyloleoylphosphatidylcholine-dipalmitoylphosphatidylcholine (POPC-DPPC) have been studied. From the surface pressure-area isotherms, elastic modulus values and virial equation coefficients can be obtained. Thermodynamic treatment also yields excess (G E ) and mixing (∆G mix ) free energies. Results indicate positive G E values, that is, molecular interactions in the mixed films are less favourable, due to the presence of unsaturation; however, the mixture is slightly favourable due to the entropic factor that affords positive ∆G mix values. For the OA-SA system, a high SA content and surface pressure facilitate the phase separation, even though a certain miscibility between both components still remains. For the POPC-DPPC system, the most favourable mixing conditions occur for X POPC ≈ 0.4. For these mixed systems, the values of the elastic modulus are more similar to those of more fluid components (OA or POPC); analysis of the virial coefficients shows that the b 1 virial coefficient values lie between those of the individual components and are higher than values suitable for an ideal mixing.

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Section: Introductionmentioning

confidence: 64%

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Torrent‐Burgués

2018

Colloids and Interfaces

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“…The larger dependence indicates the stronger affinity between the DiI-C18 with the obstacle. DiI-C18 is a cationic molecule, and the PI head group is negatively charged compared to the PC head group at pH 7.4 [ 51 ]. The electrostatic interaction enhanced the obstacle effect of the PI-derived microdomain for DiI-C18.…”

Section: Resultsmentioning

confidence: 99%

Physical Properties and Reactivity of Microdomains in Phosphatidylinositol-Containing Supported Lipid Bilayer

et al. 2021

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We characterized the size, distribution, and fluidity of microdomains in a lipid bilayer containing phosphatidylinositol (PI) and revealed their roles during the two-dimensional assembly of a membrane deformation protein (FBP17). The morphology of the supported lipid bilayer (SLB) consisting of PI and phosphatidylcholine (PC) on a mica substrate was observed with atomic force microscope (AFM). Single particle tracking (SPT) was performed for the PI+PC-SLB on the mica substrate by using the diagonal illumination setup. The AFM topography showed that PI-derived submicron domains existed in the PI+PC-SLB. The spatiotemporal dependence of the lateral lipid diffusion obtained by SPT showed that the microdomain had lower fluidity than the surrounding region and worked as the obstacles for the lipid diffusion. We observed the two-dimensional assembly of FBP17, which is one of F-BAR family proteins included in endocytosis processes and has the function generating lipid bilayer tubules in vitro. At the initial stage of the FBP17 assembly, the PI-derived microdomain worked as a scaffold for the FBP17 adsorption, and the fluid surrounding region supplied FBP17 to grow the FBP17 domain via the lateral molecular diffusion. This study demonstrated an example clearly revealing the roles of two lipid microregions during the protein reaction on a lipid bilayer.

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“…The pH-dependent change in the net charge of PPIs has been estimated from the zeta potential of PPI-containing multilamellar vesicles as shown in Fig. 2A (Ohki et al, 2010). Similar electrophoretic mobility measurements of PIP 2 vesicles in the presence of 100 mM KCl suggest that the charge of PIP 2 is approximately −3 at pH 7.0 (McLaughlin et al, 2002; Toner et al, 1988; Wang et al, 2002), and that both a proton and a potassium ion are likely bound to PIP 2 under physiologically realistic conditions.…”

Section: Physical Chemical Characterization Of Pip2 and Other Polymentioning

confidence: 99%

“…The average height of the −25 mV equipotential electrostatic surface for PIP 2 was about 17 Å away from the phospholipid (Li et al, 2009), higher than established estimates of 10 Å (McLaughlin, 1989; McLaughlin and Murray, 2005), and depends more on the tilt angle than the twist angle. Theoretical calculations of the surface (zeta) potential from (Ohki et al, 2010) that are able to reproduce the electrophoretic mobility of vesicles containing PIP or PIP 2 are sensitive to the orientation, and thus the extent of exposure, of the PIP 2 head group. The orientations that produced the highest potential surfaces were close to the most probable tilt and twist angles from the MD simulations, implying the electrostatic free energy plays in role in determining the orientation of the phospholipids.…”

Section: Simulations Of Pip2 and Its Configuration In Membranesmentioning

confidence: 99%

Counterion-mediated cluster formation by polyphosphoinositides

Wang

Slochower

Janmey

2014

Chemistry and Physics of Lipids

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Polyphosphoinositides (PPI) and in particular PI(4,5)P2, are among the most highly charged molecules in cell membranes, are important in many cellular signaling pathways, and are frequently targeted by peripheral polybasic proteins for anchoring through electrostatic interactions. Such interactions between PIP2 and proteins containing polybasic stretches depend on the physical state and the lateral distribution of PIP2 within the inner leaflet of the cell's lipid bilayer. The physical chemical properties of PIP2 such as pH-dependent changes in headgroup ionization and area per molecule as determined by experiments together with molecular simulations that predict headgroup conformations at various ionization states have revealed the electrostatic properties and phase behavior of PIP2-containing membranes. This review focuses on recent experimental and computational developments in defining the physical chemistry of PIP2 and its interactions with counterions. Ca2+-induced changes in PIP2 charge, conformation, and lateral structure within the membrane are documented by numerous experimental and computational studies. A simplified electrostatic model successfully predicts the Ca2+-driven formation of PIP2 clusters but cannot account for the different effects of Ca2+ and Mg2+ on PIP2-containing membranes. A more recent computational study is able to see the difference between Ca2+ and Mg2+ binding to PIP2 in the absence of a membrane and without cluster formation. Spectroscopic studies suggest that divalent cation- and multivalent polyamine-induced changes in the PIP2 lateral distribution in model membrane are also different, and not simply related to the net charge of the counterion. Among these differences is the capacity of Ca2+ but not other polycations to induce nm scale clusters of PIP2 in fluid membranes. Recent super resolution optical studies show that PIP2 forms nanoclusters in the inner leaflet of a plasma membrane with a similar size distribution as those induced by Ca2+ in model membranes. The mechanisms by which PIP2 forms nanoclusters and other structures inside a cell remain to be determined, but the unique electrostatic properties of PIP2 and its interactions with multivalent counterions might have particular physiological relevance.

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Surface potential of phosphoinositide membranes: Comparison between theory and experiment

Cited by 12 publications

References 42 publications

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Physical Properties and Reactivity of Microdomains in Phosphatidylinositol-Containing Supported Lipid Bilayer

Counterion-mediated cluster formation by polyphosphoinositides

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