Lateral diffusion in phospholipid bilayer membranes and multilamellar liquid crystals

Biochemistry ◽  
1978 ◽  
Vol 17 (15) ◽  
pp. 3046-3053 ◽  
Author(s):  
P. F. Fahey ◽  
W. W. Webb
Keyword(s):  
Liquid Crystals ◽  
Lateral Diffusion ◽  
Phospholipid Bilayer ◽  
Bilayer Membranes

scholarly journals Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer–leaflet and inter-leaflet coupling

2014 ◽  
Vol 470 (2167) ◽  
pp. 20130843 ◽  
Author(s):  
Reghan J. Hill ◽  
Chih-Ying Wang
Keyword(s):  
Lateral Diffusion ◽  
Bilayer Membrane ◽  
Tracer Diffusion ◽  
Phospholipid Bilayer ◽  
Supported Membranes ◽  
Bilayer Membranes ◽  
Lubrication Film ◽  
Lipid Assemblies ◽  
Slip Coefficients ◽  
Made In

A variety of observations—sometimes controversial—have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans–Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans–Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer–leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements—including lipids, integral monotopic and polytopic proteins, and lipid rafts—in supported bilayer membranes.

scholarly journals Lateral diffusion of ganglioside GM1 in phospholipid bilayer membranes

1986 ◽  
Vol 49 (4) ◽  
pp. 849-856 ◽  
Author(s):  
B. Goins ◽  
M. Masserini ◽  
B.G. Barisas ◽  
E. Freire
Keyword(s):  
Lateral Diffusion ◽  
Phospholipid Bilayer ◽  
Ganglioside Gm1 ◽  
Bilayer Membranes

Localization and preferred orientations of ubiquinone homologs in model bilayers

1992 ◽  
Vol 70 (6) ◽  
pp. 504-514 ◽  
Author(s):  
Giorgio Lenaz ◽  
Bruno Samori ◽  
Romana Fato ◽  
Maurizio Battino ◽  
Giovanna Parenti Castelli ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Fluorescence Quenching ◽  
Coenzyme Q ◽  
Nematic Liquid Crystals ◽  
Lateral Diffusion ◽  
Linear Dichroism ◽  
Two Dimensions ◽  
Phospholipid Bilayer ◽  
Guest Molecules ◽  
Site Distribution

The localization of ubiquinone has been investigated in phospholipid bilayer vesicles in studies of fluorescence quenching of membrane-bound probes by ubiquinone homologs (Qn, where n is the number of the isoprenoid units of the chain). Fluorescence-quenching data obtained by using a set of anthroylstearate probes, having the fluorophore located at different depths, revealed that ubiquinone-3 is located throughout the whole bilayer thickness. From the bimolecular quenching constants in the membrane, lateral diffusion coefficients in two dimensions were calculated to span values of 10−7–10−6 cm2∙s−1. This suggests that ubiquinones laterally diffuse in a very fluid environment. On this basis, it is proposed that their translational diffusion in the bilayer takes place in two dimensions, with the quinone ring oscillating between the two bilayer surfaces within a hydrophobic environment not extending beyond the glycerol region. This model implies that the quinonic head is both settled near the polar surface of the bilayer and buried into the host hydrocarbon interior. This two-site distribution was confirmed for all Qn, except Q0, by their linear dichroism spectra in the bilayers provided by disc-like lyotropic nematic liquid crystals. These spectra also provided detailed information on the preferential orientations of the quinonic head of the different derivatives within the two sites. The mechanism by which the localization and orientation of Qn guest molecules inside the host bilayer is modulated by the isoprenoid chain length is discussed on a thermodynamical basis. Being that Qn is expected to be also widely contained in the highly curved cristae of the mitochondrial inner membrane, by using rod-like lyotropic nematic liquid crystals we searched out effects of the curvature of the host bilayer on those Qn distributions. The linear dichroism measurements reveal that Qn guest molecules are no longer obliged to find a partition between two different types of localizations when the host bilayer is highly curved. In this case all Qn, even the longest Q10, were found to stay parallel to the amphiphilic chains with a single site localization of the head near the polar interface. By the same linear dichroism technique, the local ordering of all Qn derivatives was also evaluated. The order parameters were found to be basically the same for all derivatives. This result is justified on the basis of the relaxation, caused by the surface curvature, of the lateral compression of the host chains.Key words: coenzyme Q (ubiquinone), fluorescence quenching, lateral diffusion, linear dichroism, model bilayers.

scholarly journals Fusion of phospholipid vesicles with planar phospholipid bilayer membranes. II. Incorporation of a vesicular membrane marker into the planar membrane.

1980 ◽  
Vol 75 (3) ◽  
pp. 251-270 ◽  
Author(s):  
F S Cohen ◽  
J Zimmerberg ◽  
A Finkelstein
Keyword(s):  
Divalent Cations ◽  
Phospholipid Bilayer ◽  
Phospholipid Vesicles ◽  
Osmotic Gradient ◽  
Bilayer Membranes ◽  
Fusion Procedure ◽  
Vesicular Membrane ◽  
Membrane Contact ◽  
Planar Membrane ◽  
Planar Membranes

Fusion of multilamellar phospholipid vesicles with planar phospholipid bilayer membranes was monitored by the rate of appearance in the planar membrane of an intrinsic membrane protein present in the vesicle membranes. An essential requirement for fusion is an osmotic gradient across the planar membrane, with the cis side (the side containing the vesicles) hyperosmotic to the opposite (trans) side; for substantial fusion rates, divalent cation must also be present on the cis side. Thus, the low fusion rates obtained with 100 mM excess glucose in the cis compartment are enhanced orders of magnitude by the addition of 5-10 mM CaCl2 to the cis compartment. Conversely, the rapid fusion rates induced by 40 mM CaCl2 in the cis compartment are completely suppressed when the osmotic gradient (created by the 40 mM CaCl2) is abolished by addition of an equivalent amount of either CaCl2, NaCl, urea, or glucose to the trans compartment. We propose that fusion occurs by the osmotic swelling of vesicles in contact with the planar membrane, with subsequent rupture of the vesicular and planar membranes in the region of contact. Divalent cations catalyze this process by increasing the frequency and duration of vesicle-planar membrane contact. We argue that essentially this same osmotic mechanism drives biological fusion processes, such as exocytosis. Our fusion procedure provides a general method for incorporating and reconstituting transport proteins into planar phospholipid bilayer membranes.

scholarly journals High Pressure Bioscience. Phospholipid Bilayer Membranes under High Pressure.

1999 ◽  
Vol 9 (3) ◽  
pp. 213-220 ◽  
Author(s):  
Shoji KANESHINA ◽  
Hitoshi MATSUKI ◽  
Hayato ICHIMORI
Keyword(s):  
High Pressure ◽  
Phospholipid Bilayer ◽  
Bilayer Membranes
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