Model membranes: Spherical shells bounded by one bimolecular layer of phospholipids

Seufert, Wolf D.

doi:10.1007/bf01189465

Cited by 34 publications

(5 citation statements)

References 12 publications

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“…4 of Tsong and Kingsley, 1975). The fast biphasic decrease in turbidity (T, -20 gs and T2 -5 ms) is consistent with a swelling of the red cells (Seufert, 1970;Yi and MacDonald, 1973). There is much experimental evidence to suggest that these signals arise from the water relaxations in the membrane structures (Tsong and Kingsley, 1975;Owen et al, 1970a,b).…”

Section: Water Relaxationsmentioning

confidence: 59%

Relaxation phenomena in human erythrocyte suspensions

Tsong

Kingsley

et al. 1976

Biophysical Journal

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Previous work has shown that the application of the Joule heating temperature jump technique of Eigen and de Maeyer to an istonic suspension of human erythrocytes induced an interiorization of [3H-A1glucose and a hemolysis of the red cells (Tsong, T.Y., and E. Kingsley, J. Biol. Chem. 250:786 [1975]). The result was interpreted as due to the thermal osmosis effect. Further considerations of the various effects of the Joule heating technique indicate that the hemolysis of the red cells may also be caused by the rapid dielectric perturbation of the cell membranes. By means of turbidity measurements of the suspensions we have detected at least four relaxation times. Two of the faster ones (tau1 approximately 20 mus and tau2 approximately 5 ms) are tentatively attributed to water relaxations in the membrane structures. The other two are attributed to membrane ruptures (tlag approximately 0.1s) and the hemolysis reaction (tau3 approximately 0.5 s). Studies with the erythrocytes from different hematological disorders indicate that whereas the two slower relaxations are sensitive to the overall physical property of the red cell membranes the two faster relaxations are not. These observations are consistent with the above assignment of the relaxation processes. The apparent activation energies are, above assignment of the relaxation processes. The apparent activation energies are, respectively, 8.4, 12.0, and 11.8 kcal/mol for the tau1, tau2, and tau3 reactions. Experiments with erythrocyte ghosts indicate a single relaxation for the water permeation, and biphasic kinetics for the membrane rupture and resealing reactions. The phenomena reported here may contribute to our understanding of water transport and molecular release in cellular systems.

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Section: Water Relaxationsmentioning

confidence: 59%

Relaxation phenomena in human erythrocyte suspensions

Tsong

Kingsley

et al. 1976

Biophysical Journal

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“…b ß equals R"6/k2 where Rtl6 = (8.785 X 1 O8)k20d" 4 (7 X 1 O'5), k2 is the orientation factor for dipole-dipole interaction [see Dale & Eisinger (1974)], </>q is the donor quantum yield in the absence of acceptor, and n is the refractive index of the lipid bilayer. The values used for calculation of ß were = 1.455 (Cherry & Chapman, 1969;Seufert, 1970;Yi & MacDonald, 1973) and </>d = 0.522 [using = 0.14 for tryptophan in water at 25 °C; Eisinger (1969)].…”

Section: Methodsmentioning

confidence: 99%

Intramembrane position of the fluorescent tryptophanyl residue in membrane-bound cytochrome b5

Fleming¹,

Koppel²,

Lau³

et al. 1979

Biochemistry

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We have developed a method to measure the intramembrane position of the fluorescent tryptophanyl residue in whole cytochrome b5 and the nonpolar membrane binding segment when these molecules are bound to phospholipid vesicles [Koppel, D.E., Fleming, P., & Strittmatter, P. (1979) Biochemistry (preceding paper in this issue)]. The method utilizes excitation energy transfer from the donor tryptophanyl residue in the protein to trinitrophenyl or danysl acceptor groups on the surface of the phospholipid bilayer. It was determined that that single fluorescent tryptophanyl residue in vesicle-bound cytochrome b5 and the nonpolar segment is located approximately 20-22 A below the surface of the bilayer. This position represents a minimum depth of penetration of this portion of the cytochrome in the membrane.

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“…In the present work, the above hypothesis has been tested using the membrane permeant CCCP - as the organic anion and soybean phospholipid (SBPL) vesicles in aqueous solutions as model membrane systems in view of the data already available in the literature and other advantages of SBPL vesicular membranes mentioned elsewhere. ,− Representative experiments have also been carried out using vesicles prepared from phosphotidylcholine (PC) + 6% phosphatidic acid (PA) lipid mixtures.…”

Section: Introductionmentioning

confidence: 99%

Barriers to Translocation of Organic Ions in Phospholipid Membranes

Prabhananda

Kombrabail

1998

J. Phys. Chem. B

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The hypothesis that a dominant barrier to the translocation of organic ions (such as carbonyl cyanide m-chlorophenylhydrazone (CCCP)) across phospholipid bilayer membranes is located between the “polar region” and “nonpolar region” of the membrane layer has been confirmed by the following observation: The rate of decay of the pH difference across soybean phospholipid vesicular membrane (ΔpH) increased substantially when the above substep was specifically catalyzed. In our strategy, the formation of the electroneutral ternary complex valinomycin−M+−CCCP- (M+ = K+, Cs+) affects this substep. Also, CCCP- ion translocation is facilitated by having an alternate path for the compensating charge flux of alkali metal ions through gramicidin channels. The observed enhancement behaviors on changing the lipid composition from soybean phospholipid (SBPL) to a mixture of PC + 6% PA, weak acid from CCCP to carbonyl cyanide 4-trifluoromethoxyphenylhydrazone (FCCP), and the metal ion from K+ to Cs+ are consistent with the predictions of the suggested mechanisms. The increase in the ΔpH decay rate on increasing the ionic strength confirms the Coulombic nature of a dominant interaction between the CCCP- ion and the lipid contributing to the kinetic barrier. Even though the gross features of the ion translocation barrier profile inferred by us are similar to that given in the literature, our results suggest the need to consider ion translocation across the phospholipid membrane to involve at least three substeps. This requires a refinement of the barrier profile given in the literature. In our experiments, the ΔpH was created by temperature jump, and observations on the ΔpH decay were made by monitoring the fluorescence from the pyranine entrapped inside the vesicles.

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Model membranes: Spherical shells bounded by one bimolecular layer of phospholipids

Cited by 34 publications

References 12 publications

Relaxation phenomena in human erythrocyte suspensions

Relaxation phenomena in human erythrocyte suspensions

Intramembrane position of the fluorescent tryptophanyl residue in membrane-bound cytochrome b5

Barriers to Translocation of Organic Ions in Phospholipid Membranes

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