Deuteron nuclear magnetic resonance study of the dynamic organization of phospholipid/cholesterol bilayer membranes: Molecular properties and viscoelastic behavior

Journal Article · Tue Feb 04 00:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00119a019· OSTI ID:5687841

Weisz, K; Groebner, G; Mayer, C; Stohrer, J; Kothe, G ^[1]

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1. Univ. Stuttgart (West Germany)

The influence of cholesterol on the dynamic organization of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers was studied by deuteron nuclear magnetic resonance ({sup 2}H NMR) using unoriented and macroscopically aligned samples. Analysis of the various temperature- and orientation-dependent experiments was performed using a comprehensive NMR model based on the stochastic Liouville equation. Computer simulations of the relaxation data obtained from phospholipids deuterated at the 6-, 13- and 14-position of the sn-2 chain and cholesterol labeled at the 3{alpha}-position of the rigid steroid ring system allowed the unambiguous assignment of the various motional modes and types of molecular order present in the system. Above the phospholipid gel-to-liquid-crystalline phase transition, T{sub M}, 40 mol % cholesterol was found to significantly increase the orientational and conformational order of the phospholipid with substantially increased trans populations even at the terminal sn-2 acyl chain segments. Lowering the temperature continuously increases both inter- and intramolecular ordering, yet indicates less ordered chains than found for the pure phospholipid in its paracrystalline gel phase. Trans-gauche isomerization rates on all phospholipid alkyl chain segments are slowed down by incorporated cholesterol to values characteristic of gel-state lipid. Analysis of these collective lipid motions provides the viscoelastic parameters of the membranes. The results show that cholesterol significantly reduces the density of the cooperative motions by increasing the average elastic constant of the membrane.

• OSTI ID: 5687841
• Journal Information: Biochemistry; (United States), Vol. 31:4; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MEMBRANES
PHASE STUDIES
PHOSPHOLIPIDS
NUCLEAR MAGNETIC RESONANCE
CHOLESTEROL
ISOMERIZATION
MOLECULAR STRUCTURE
TEMPERATURE DEPENDENCE
CHEMICAL REACTIONS
ESTERS
HYDROXY COMPOUNDS
LIPIDS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
RESONANCE
STEROIDS
STEROLS
550201* - Biochemistry- Tracer Techniques