Dependence of deuterium spin-lattice relaxation rates of multilamellar phospholipid dispersions on orientational order

Gerald D. Williams, James M. Beach, Steven W. Dodd, Michael F Brown

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

2H NMR studies of a homologous series of 1,2-diacyl-sn-glycero-3-phosphocholines with perdeuterated saturated chains, ranging in length from C12:0 to C16:0, have been performed with use of quadrupolar echo techniques at a resonance frequency of 55.4 MHz. Randomly oriented, multilamellar dispersions containing 50 wt % H2O in the liquid crystalline (Lα) phase have been employed. The 2H spin-lattice relaxation times (T1) and C-2H bond segmental order parameters (SCD) of each of the resolved quadrupolar splittings have been obtained from the powder-type spectra, corresponding to a random distribution of orientations, as well as from the 0°C oriented subspectra obtained by numerical deconvolution (de-Pakeing). Evidence that the spin-lattice relaxation rate profiles as a function of chain position T1-1(i) are related to the corresponding order profiles SCD(i) by a square-law functional dependence has been obtained, indicative of a contribution from relatively slow fluctuations in the local bilayer ordering to the relaxation. The results suggest that two broad classes of motions influence the 2H spin-lattice relaxation rates of lipid bilayers: rapid local motions, most likely due to bond rotational isomerizations and long-axis rotational diffusion of the lipid chains, as well as slower director fluctuations as found in other liquid crystalline mesophases.

Original languageEnglish (US)
Pages (from-to)6868-6873
Number of pages6
JournalJournal of the American Chemical Society
Volume107
Issue number24
StatePublished - 1985
Externally publishedYes

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Spin-lattice relaxation
Deuterium
Phospholipids
Dispersions
Phosphorylcholine
Lipid Bilayers
Powders
Crystalline materials
Lipid bilayers
Liquids
Deconvolution
Isomerization
Lipids
Relaxation time
Nuclear magnetic resonance

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Dependence of deuterium spin-lattice relaxation rates of multilamellar phospholipid dispersions on orientational order. / Williams, Gerald D.; Beach, James M.; Dodd, Steven W.; Brown, Michael F.

In: Journal of the American Chemical Society, Vol. 107, No. 24, 1985, p. 6868-6873.

Research output: Contribution to journalArticle

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N2 - 2H NMR studies of a homologous series of 1,2-diacyl-sn-glycero-3-phosphocholines with perdeuterated saturated chains, ranging in length from C12:0 to C16:0, have been performed with use of quadrupolar echo techniques at a resonance frequency of 55.4 MHz. Randomly oriented, multilamellar dispersions containing 50 wt % H2O in the liquid crystalline (Lα) phase have been employed. The 2H spin-lattice relaxation times (T1) and C-2H bond segmental order parameters (SCD) of each of the resolved quadrupolar splittings have been obtained from the powder-type spectra, corresponding to a random distribution of orientations, as well as from the 0°C oriented subspectra obtained by numerical deconvolution (de-Pakeing). Evidence that the spin-lattice relaxation rate profiles as a function of chain position T1-1(i) are related to the corresponding order profiles SCD(i) by a square-law functional dependence has been obtained, indicative of a contribution from relatively slow fluctuations in the local bilayer ordering to the relaxation. The results suggest that two broad classes of motions influence the 2H spin-lattice relaxation rates of lipid bilayers: rapid local motions, most likely due to bond rotational isomerizations and long-axis rotational diffusion of the lipid chains, as well as slower director fluctuations as found in other liquid crystalline mesophases.

AB - 2H NMR studies of a homologous series of 1,2-diacyl-sn-glycero-3-phosphocholines with perdeuterated saturated chains, ranging in length from C12:0 to C16:0, have been performed with use of quadrupolar echo techniques at a resonance frequency of 55.4 MHz. Randomly oriented, multilamellar dispersions containing 50 wt % H2O in the liquid crystalline (Lα) phase have been employed. The 2H spin-lattice relaxation times (T1) and C-2H bond segmental order parameters (SCD) of each of the resolved quadrupolar splittings have been obtained from the powder-type spectra, corresponding to a random distribution of orientations, as well as from the 0°C oriented subspectra obtained by numerical deconvolution (de-Pakeing). Evidence that the spin-lattice relaxation rate profiles as a function of chain position T1-1(i) are related to the corresponding order profiles SCD(i) by a square-law functional dependence has been obtained, indicative of a contribution from relatively slow fluctuations in the local bilayer ordering to the relaxation. The results suggest that two broad classes of motions influence the 2H spin-lattice relaxation rates of lipid bilayers: rapid local motions, most likely due to bond rotational isomerizations and long-axis rotational diffusion of the lipid chains, as well as slower director fluctuations as found in other liquid crystalline mesophases.

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