The adsorption of divalent cations to phosphatidylglycerol bilayer membranes

Lau, Arthur L. Y.; McLaughlin, Alan C.; McLaughlin, Stuart

doi:10.1016/0005-2736(81)90199-1

Cited by 156 publications

(107 citation statements)

References 37 publications

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“…Like monovalent cations, bivalent cations strongly bind to acidic phospholipids [35,31,57,[59][60][61][62]. Cations have also been shown to interact with phosphatidylcholine, a zwitterionic lipid [49, 65,661.…”

Section: Discussionmentioning

confidence: 99%

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Lakhdar-Ghazal

Tichadou

Tocanne

1983

European Journal of Biochemistry

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Ionization of the acidic phospholipid phosphatidylglycerol has been studied by measuring the surface potential of monomolecular films of the lipid as a function of the aqueous subphase pH and the concentration of monovalent cations (Li, Na, Cs). It is shown that theexperimental data can be interpreted by means of the Gouy-Chapman theory in its simplest formulation, provided an adsorption of cations at the membrane surface is accounted for. This allows us to predict the ionization state of the lipid for given ionic conditions in the subphase. Above pH 4, for subphase ion concentration higher than 10 mM, or for ion concentrations above 0.1 mM at pH 5.6, phosphatidylglycerol is fully deprotonated. Within the limits of our theoretical approach, association constants of the cations to the lipid lie around 0.1-0.6 M-I.With the exception of phosphatidylcholine and phosphatidylethanolamine which are zwitterions over a large pH range (3 -8) [l], phospholipids in biomembranes are acidic substances bearing a net negative charge when they are ionized. Ionization or protonation of these acidic lipids as well as their interactions with cations can have considerable consequences on both membrane structure and functions.From a structural point of view, changes in the pH or the ionic strength of the aqueous phase have been shown to trigger phase transition of acidic phospholipids [2-111. The bivalent cations Mg2+ and Ca2+ can bring about phase separation within mixtures of zwitterionic and acidic phospholipids [12-191. Cations can also modify the dynamic properties of lipids, i.e. their lateral diffusion rate [20], as well as being able to promote morphological changes [21]. As an example, cardiolipin, which normally exists in a lamellar phase in the presence of sodium, adopts the hexagonal H,, phase in the presence of calcium [22, 231. Dipalmitoylglycerophosphoglycerol, which normally stays in a lamellar phase in the presence of sodium, has been shown to exist in an interdigitated phase in the presence of the organic cations choline and acetylcholine [24].From a functional point of view, phospholipids can modulate the activity of membrane enzymes by monitoring, at the membrane surface, a concentration of protons, cations and of any charged metabolites which is quite different from that existing in the bulk [25]. Charges at the membrane surface also contribute to the establishment of transmembrane potentials which are involved in energy-linked transmembrane transport processes [26] and which are postulated to monitor the orientation [27 -291 and the activity of certain membrane proteins [28 -341.For all these reasons, it is of great importance to have a full understanding of the ionization process of acidic phospholipids in membrane systems. This would allow a correct prediction of their ionization state and of the surface potential they generate, for given ionic conditions in the aqueous phase. As a first approach, ionization of phosphatidylglycerol was studied in monolayers by measuring changes in film surface pressure again...

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Section: Discussionmentioning

confidence: 99%

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Lakhdar-Ghazal

Tichadou

Tocanne

1983

European Journal of Biochemistry

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“…A combination of the equations above may be considered a rendition of the Gouy-Chapman-Stern model (16). The model we employ in this article, together with the values for the parameters, was derived from the literature without reference to our own data.…”

Section: Methodsmentioning

confidence: 99%

“…Subsequently, the model was applied to our data without adjustment of parameters. were derived from several sources (7,16,24). KH,P was assigned the value of the reciprocal of the first dissociation constant for phosphoric acid.…”

Section: Methodsmentioning

confidence: 99%

“…Negative charges, located in the cell wall and on the plasma membrane, are carried on the carboxylate groups of cell-wall pectins, the residues of acidic amino acids in membrane proteins, and the phosphate groups of membrane phospholipids (16,19,23). The charges on the cell surface create electrical potential gradients that interact with the distribution of ions (5,18,19).…”

Section: Introductionmentioning

confidence: 99%

“…It may be impossible to differentiate formally the two hypotheses for H+ amelioration of Al toxicity or to establish the rhizotoxicity of all of the Al species (12), but in this article we shall argue that Al" is toxic and that Al3" toxicity, specifically, is ameliorated by H+ and other cations. The argument will rest upon new data that support the hypothesis that the negatively charged cell surfaces in the root accumulate A13+ and other toxic cations, and that amelioration is effected by treatments that reduce the negativity of the cellsurface electrical potential.Negative charges, located in the cell wall and on the plasma membrane, are carried on the carboxylate groups of cell-wall pectins, the residues of acidic amino acids in membrane proteins, and the phosphate groups of membrane phospholipids (16,19,23). The charges on the cell surface create electrical potential gradients that interact with the distribution of ions (5,18,19).…”

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Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Kinraide¹,

Ryan²,

Kochian³

1992

Plant Physiol.

269

161

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The rhizotoxicities of Al3" and of La3" to wheat (Triticum aestivum L.) were similarly ameliorated by cations in the following order of effectiveness: H -C3 > C2 > C1'. Among tested cations of a given charge, ameliorative effectiveness was similar except that Ca2' was slightly more effective than other divalent cations and H' was much more effective than other monovalent cations. H' rhizotoxicity was also ameliorated by cations in the order C3' > C2 > C1". These results suggest a role for cell-surface electrical potential in the rhizotoxicity of Al3", La3, H', and other toxic cations: negatively charged cell surfaces of the root accumulate the toxic cations, and amelioration is effected by treatments that reduce the negativity of the cell-surface electrical potential by charge screening or cation binding. Membrane whose toxicity has not been established. It may be impossible to differentiate formally the two hypotheses for H+ amelioration of Al toxicity or to establish the rhizotoxicity of all of the Al species (12), but in this article we shall argue that Al" is toxic and that Al3" toxicity, specifically, is ameliorated by H+ and other cations. The argument will rest upon new data that support the hypothesis that the negatively charged cell surfaces in the root accumulate A13+ and other toxic cations, and that amelioration is effected by treatments that reduce the negativity of the cellsurface electrical potential.Negative charges, located in the cell wall and on the plasma membrane, are carried on the carboxylate groups of cell-wall pectins, the residues of acidic amino acids in membrane proteins, and the phosphate groups of membrane phospholipids (16,19,23). The charges on the cell surface create electrical potential gradients that interact with the distribution of ions (5,18,19). Salts in the bathing medium reduce the negative surface potential in two ways: by cation binding and by charge screening. Because of the binding of H+ with carboxylate, phosphate, and amino groups, charge reversal of the plasma membrane surface can occur as the pH there drops below 4 (22). Divalent and polyvalent cations can also bind, and the latter can cause charge reversals at the membrane surface (1, 21). Charge screening occurs because coulombic attractions concentrate cations around the cell-surface negative charges. The effectiveness of the cations in charge screening increases with cation valence according to basic electrostatic models (5,18,19).Amelioration of Al toxicity by H+ and other cations can be interpreted as evidence of the influence of cell surface charge on Al toxicity, but another line of evidence also suggests the same conclusion. Several reports indicate that within closely related taxa, higher varietal sensitivity to Al corresponds to higher varietal cation exchange capacity of whole roots (8, 27, and

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Binding of a Ruthenium Complex to a Thioether Ligand Embedded in a Negatively Charged Lipid Bilayer: A Two‐Step Mechanism

Bahreman

Rabe

Kros

et al. 2014

Chemistry A European J

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The interaction between the ruthenium polypyridyl complex [Ru(terpy)(dcbpy)(H2O)](2+) (terpy = 2,2';6',2"-terpyridine, dcbpy = 6,6'-dichloro-2,2'-bipyridine) and phospholipid membranes containing either thioether ligands or cholesterol were investigated using UV-visible spectroscopy, Langmuir-Blodgett monolayer surface pressure measurements, and isothermal titration calorimety (ITC). When embedded in a membrane, the thioether ligand coordinated to the dicationic metal complex only when the phospholipids of the membrane were negatively charged, that is, in the presence of attractive electrostatic interaction. In such a case coordination is much faster than in homogeneous conditions. A two-step model for the coordination of the metal complex to the membrane-embedded sulfur ligand is proposed, in which adsorption of the complex to the negative surface of the monolayers or bilayers occurs within minutes, whereas formation of the coordination bond between the surface-bound metal complex and ligand takes hours. Finally, adsorption of the aqua complex to the membrane is driven by entropy. It does not involve insertion of the metal complex into the hydrophobic lipid layer, but rather simple electrostatic adsorption at the water-bilayer interface.

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The adsorption of divalent cations to phosphatidylglycerol bilayer membranes

Cited by 156 publications

References 37 publications

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Binding of a Ruthenium Complex to a Thioether Ligand Embedded in a Negatively Charged Lipid Bilayer: A Two‐Step Mechanism

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The adsorption of divalent cations to phosphatidylglycerol bilayer membranes

Cited by 156 publications

References 37 publications

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Effect of pH and Monovalent Cations on the Ionization State of Phosphatidylglycerol in Monolayers

Interactive Effects of Al3+, H+, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Binding of a Ruthenium Complex to a Thioether Ligand Embedded in a Negatively Charged Lipid Bilayer: A Two‐Step Mechanism

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Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential