Ionic structure of phospholipid membranes, and binding of calcium ions

Seimiya, Tsutomu; Ohki, Shinpei

doi:10.1016/0005-2736(73)90073-4

Cited by 194 publications

(61 citation statements)

References 58 publications

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“…Fig. 5 B shows the double-reciprocal plot according to Equation (8). From the straight line obtained by least-squares analysis the intercept 1 /n = 1.15 and the slope l/K,n = 2 x lo-' were obtained.…”

Section: Dissociation Equilibria In Phosphatidylserinementioning

confidence: 99%

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Ion‐Binding to Phospholipids

Häuser¹,

Darke

Phillips

1976

European Journal of Biochemistry

142

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The binding of Ca2+ to monolayers and bilayers of phosphatidylserine has been investigated as a function of pH, ionic strength (NaCl concentration) and Ca2+ concentration using surface and colloid chemical techniques. The molar ratio of lipid to bound calcium decreases to 2 as the Ca2+ concentration is increased to about 0.1 mM. At [Ca2+] > 0.1 mM a 1:1 complex is formed. The apparent binding constant Ka ranges from about ∼ 106‐−104 l/mol depending on the Ca2+ concentration. After allowing for electrostatic effects and neighbour group interactions, the intrinsic binding constant Ki of the phosphorylserine polar group at pH 7 (I= 0.01 M), where it carries a net negative charge of one, is ∼ 104 l/mol; consistent values for Ki were obtained using several independent approaches. Ka for Ca2+ binding decreases with increasing NaCl concentration because the monovalent cations compete with Ca2++ for the same binding site. Na+ and K+ are equally effective in displacing 45Ca2+ adsorbed to monolayers of phosphatidylserine, both with respect to the kinetics and the equilibrium of the displacement. Ka for the reaction between phosphatidylserine and monovalent cations is about 103‐fold smaller than that of Ca2+. An investigation of the binding of Mn2+ to phosphatidylserine by both surface chemical and nuclear magnetic resonance methods shows that this cation has a similar binding constant to that of Ca2+. The Ca2+ ‐binding capabilities of monolayers containing only carboxyl groups (i.e. arachidic acid) and phosphodiester groups (i.e. dicetyl phosphate) have also been determined; the apparent pK for the –COOH group in monolayers is ⋧ 9 and that for the phosphodiester group is < 4. Since these groups do not retain the same pK values when they are in close proximity in the phosphorylserine group, the relative contributions of the two groups to the binding of Ca2+ to phosphatidylserine, is not obvious.

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Section: Dissociation Equilibria In Phosphatidylserinementioning

confidence: 99%

“…The apparent pK of the carboxyl group of phosphatidylserine derived from the variation of the electrophoretic mobility with pH is 4.3 [5,8,19] (see Appendix). This is lower than the pK value of 5.2 derived from the 45CaZ+ adsorption result (see Appendix).…”

Section: Apparent P K Values Of the Different Ionizable Groups Constimentioning

confidence: 99%

Ion‐Binding to Phospholipids

Häuser¹,

Darke

Phillips

1976

European Journal of Biochemistry

142

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“…In contrast, at all the pHs tested, after treatment 3 the erythrocytes showed mobility that was almost identical with that of the control cells which had had no treatment. These facts indicate that the increased mobility at these alkaline pH values reflects an increase in the negative charges produced by dissociation of the anionic head groups of the amphiphilic lipid molecules added or formed in the outer half of the lipid bilayer in the pH range of 6 to 8 because the COOH group of a long-chain fatty acid and the second OH of the phosphoric acid in the phosphatidic acid molecules in a monolayer or bilayer state dissociated in this pH range (6).…”

Section: Resultsmentioning

confidence: 99%

Detection of the electrical surface charge induced by treatment of the membrane lipid bilayer of human erythrocytes.

Tamura

Morita

Fujii

et al. 1982

Cell Struct. Funct.

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ABSTRACT.The lipid bilayer of the membrane of human erythrocytes from which most sialic acid residues on the outer surface had been removed was digested by phospholipase from outside the medium or treated by the incorpora- We reported previously that a change in the shape of human erythrocytes is induced by in vitro treatments of the membrane lipid bilayer (1,8) and that after some treatments which liberate or form anionic head groups in the lipid molecules exposed on the outer surface of the membrane, the degree of the change in shape became markedly dependent on the pH of the medium (8, 9). We assumed that the dissociation of these polar head groups in an appropriate pH range might increase the repulsion among the charged groups or increase the hydration around these groups. This in turn would result in the asymmetric expansion of the outer half of the lipid bilayer, relative to the inner half because the mechanism for the change in the shape of the erythrocytes can be explained by the asymmetric expansion of one half of the bilayer according to the "bilayer couple hypothesis" (7) . To prove the validity of our assumption, we have demonstrated by cell electrophoresis that these treatments do cause the increased exposure of dissociable head groups on the bilayer outer surface, and that these groups become negatively charged in the pH range of their dissociation. We used desialydated erythrocytes which had been treated with neuraminidase to remove most of the sialic acid residues on their outer surfaces because the abundant negative charges of these residues must prevent the electrophoretic detection of the relatively weak negative charges contributed by the polar head groups of the membrane lipids.

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“…On the other hand, the perfect reversibility of the effect of external pH changes also suggest that pH might (i) induce changes in the molecular configuration around a pKa value, (ii) alter the insertion of the molecule into the membrane, (iii) modify the degree of availability of negative surface charges and (iv) alter the amount of Ca2+ bound to the external side of the membrane. Low pH is known to displace Ca2 + from the phospholipids phosphate and carboxyl groups (Seimiya & Ohki, 1973;Hille et al, 1975).…”

Section: Discussionmentioning

confidence: 99%

Characterization of the palytoxin‐induced sodium conductance in frog skeletal muscle

Ecault

Sauviat

1991

British J Pharmacology

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The effects of palytoxin (PTX) on transmembrane potentials and currents of frog skeletal muscle were analyzed by intracellular microelectrode techniques and the double sucrose-gap voltage clamp method. 2 PTX irreversibly depolarized the membrane. The depolarization was Na-sensitive. 3 Under voltage clamp, PTX induced an inward resting current which did not inactivate, was inhibited by external Na+ removal and was a function of external Na concentration.4 This resting current could be carried either by Na+, Li', K+ or by guanidinium according to the permeability sequence K+ < Li+ < Na+ < Gua+. 5The PTX-induced current was only weakly sensitive to tetrodotoxin. It was reversibly and dosedependently inhibited by amiloride with a one to one stoichiometry and a KD of 0.3 mm. 6 Acidic pH partially inhibited the current induced by PTX which was also highly sensitive to external Cd2 + and La3 + The inhibitory sequence for divalent cations was: Mg2 + < Ca2 + = Ba2 + = Mn2+ < Cd2;with La3" > Cd2.7 The amplitude of the PTX-induced Irest was markedly reduced in the absence of external Ca2 + 8 PTX induced a Na+ resting conductance in frog skeletal muscle. The size of the channel induced by PTX is larger than the guanidinium ion. External membrane Ca2+ might be a cofactor involved in the mode of action of PTX.

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Ionic structure of phospholipid membranes, and binding of calcium ions

Cited by 194 publications

References 58 publications

Ion‐Binding to Phospholipids

Ion‐Binding to Phospholipids

Detection of the electrical surface charge induced by treatment of the membrane lipid bilayer of human erythrocytes.

Characterization of the palytoxin‐induced sodium conductance in frog skeletal muscle

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