Magnetic resonance studies of membrane and model membrane systems. V. Comparisons of aqueous dispersions of pure and mixed phospholipids

Journal Article · Mon Dec 31 00:00:00 EST 1973 · Ann. N.Y. Acad. Sci.; (United States)

DOI:https://doi.org/10.1111/j.1749-6632.1973.tb15281.x· OSTI ID:6478229

Horwitz, A F; Klein, M P; Michaelson, D M; Kohler, S J

Phospholipid regions in cellular membranes are involved in a variety of functions, including the maintenance of permeability barriers and associations with some proteins to form functional entities. The evidence available from several physical techniques suggests that in nearly all of the membranes studied there are regions in which phospholipids are arranged in bilayers which exhibit varying degrees of mobility (or fluidity). The bilayer arrangement of phospholipids in cellular membranes is not accidental; it is a manifestation of their amphiphilic nature, and it occurs when they are isolated and dispersed into water. Since the phospholipids spontaneously form bilayer structures in water that are similar to those found in cellular membranes, and since phospholipids in lipid-water model systems are more easily studied than those in complicated membranes, it has been assumed that bilayers composed of aqueous phospholipid dispersions provide a reasonable model and convenient point of departure for studying the phospholipids in membranes. Partial solutions to questions concerning the nature of phospholipid bilayers are beginning to emerge from the results of several physical techniques. Of these techniques, NMR has been of great use in elucidating the motion of the fluid fatty acids of lecithin. In particular, T/sub 1/ measurements have provided information concerning fast processes, and T/sub 2/ measurements have provided information about relatively slower processes. This paper discussed briefly some relevant topics in relaxation theory, review work on both sonicated and unsonicated lecithins and the dynamic model that is proposed to explain the relaxation data, report some effects of altered fatty acid composition on the NMR parameters, report results concerning the interactions of cations with two phospholipids; phosphatidylcholine which is zwitterionic and phosphatidylglycerol (PG) which is anionic, and, finally, the behavior of aqueous dispersions of PC--PG mixtures.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 6478229
• Journal Information: Ann. N.Y. Acad. Sci.; (United States), Vol. 222
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AQUEOUS SOLUTIONS
DISPERSIONS
LECITHINS
MEMBRANES
MAGNETIC RESONANCE
PHOSPHOLIPIDS
COMPARATIVE EVALUATIONS
SPIN-LATTICE RELAXATION
MATHEMATICAL MODELS
BIOCHEMISTRY
CARBOXYLIC ACIDS
CATIONS
CELL MEMBRANES
RELAXATION
CELL CONSTITUENTS
CHARGED PARTICLES
CHEMISTRY
ESTERS
IONS
LIPIDS
MIXTURES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
RESONANCE
SOLUTIONS
550200* - Biochemistry
550300 - Cytology