Configurational statistics of acyl chains in polyunsaturated lipid bilayers from 2H NMR

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

Research output: Contribution to journalArticle

97 Citations (Scopus)

Abstract

To gain a better understanding of the biological roles of polyunsaturated phospholipids, deuterium (2H) NMR studies have been conducted of 1-perdeuteriopalmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, an asymmetric or mixed-chain saturated-polyunsaturated phospholipid, in the liquid crystalline (Lα) phase. The palmitoyl (16:0) chain at the glycerol sn-1 position was labeled with 2H by perdeuteration, whereas the polyunsaturated, docosahexaenoyl (22:6ω3) chain at the sn-2 position was unlabeled, i.e., protiated. The 2H NMR results were compared to studies of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which both the sn-1 and sn-2 palmitoyl chains were perdeuterated, as well as 1-palmitoyl-2-perdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which only the sn-2 chain was perdeuterated. Multilamellar phospholipid dispersions containing 50 wt % H2O were employed, and 2H NMR spectra were obtained using quadrupolar echo methods at a magnetic field strength of 8.5 T. The experimental 2H NMR spectra were numerically deconvolved (de-Paked) to yield subspectra corresponding to the parallel bilayer orientation with respect to the main applied magnetic field. The increased resolution of the de-Paked subspectra enabled profiles of the segmental order parameters of the individual C-2H bonds, denoted by |SCD(i)|, to be derived as a function of chain position. Significant differences in the 2H NMR spectra and derived |SCD(i)| profiles of the per-2H-16:0 chains of the polyunsaturated and saturated bilayers were found. Based on simplified statistical mechanical theories, the differences can be interpreted in terms of an increase in the configurational freedom of the palmitoyl chains in the polyunsaturated bilayer, relative to bilayers of phosphatidylcholines with two identical saturated chains. The increased configurational freedom may correspond to an increase in the equilibrium area per chain in the case of the polyunsaturated bilayer. Possible further interpretations of the results in terms of the thickness of the hydrocarbon region and the presence or lack of interdigitation of the polyunsaturated and saturated acyl chains are also briefly discussed. We conclude that the configurational properties of the acyl chains of polyunsaturated bilayers are significantly different from those of saturated phospholipid bilayers.

Original languageEnglish (US)
Pages (from-to)2600-2609
Number of pages10
JournalJournal of the American Chemical Society
Volume109
Issue number9
StatePublished - 1987
Externally publishedYes

Fingerprint

Lipid bilayers
Lipid Bilayers
Phospholipids
Phosphorylcholine
Nuclear magnetic resonance
Statistics
Magnetic Fields
Deuterium
Magnetic fields
Hydrocarbons
Phosphatidylcholines
Glycerol
Dispersions
Crystalline materials
Liquids

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Configurational statistics of acyl chains in polyunsaturated lipid bilayers from 2H NMR. / Salmon, Amir; Dodd, Steven W.; Williams, Gerald D.; Beach, James M.; Brown, Michael F.

In: Journal of the American Chemical Society, Vol. 109, No. 9, 1987, p. 2600-2609.

Research output: Contribution to journalArticle

Salmon, Amir ; Dodd, Steven W. ; Williams, Gerald D. ; Beach, James M. ; Brown, Michael F. / Configurational statistics of acyl chains in polyunsaturated lipid bilayers from 2H NMR. In: Journal of the American Chemical Society. 1987 ; Vol. 109, No. 9. pp. 2600-2609.
@article{fec621c31052458faf2b3c50ba874b92,
title = "Configurational statistics of acyl chains in polyunsaturated lipid bilayers from 2H NMR",
abstract = "To gain a better understanding of the biological roles of polyunsaturated phospholipids, deuterium (2H) NMR studies have been conducted of 1-perdeuteriopalmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, an asymmetric or mixed-chain saturated-polyunsaturated phospholipid, in the liquid crystalline (Lα) phase. The palmitoyl (16:0) chain at the glycerol sn-1 position was labeled with 2H by perdeuteration, whereas the polyunsaturated, docosahexaenoyl (22:6ω3) chain at the sn-2 position was unlabeled, i.e., protiated. The 2H NMR results were compared to studies of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which both the sn-1 and sn-2 palmitoyl chains were perdeuterated, as well as 1-palmitoyl-2-perdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which only the sn-2 chain was perdeuterated. Multilamellar phospholipid dispersions containing 50 wt {\%} H2O were employed, and 2H NMR spectra were obtained using quadrupolar echo methods at a magnetic field strength of 8.5 T. The experimental 2H NMR spectra were numerically deconvolved (de-Paked) to yield subspectra corresponding to the parallel bilayer orientation with respect to the main applied magnetic field. The increased resolution of the de-Paked subspectra enabled profiles of the segmental order parameters of the individual C-2H bonds, denoted by |SCD(i)|, to be derived as a function of chain position. Significant differences in the 2H NMR spectra and derived |SCD(i)| profiles of the per-2H-16:0 chains of the polyunsaturated and saturated bilayers were found. Based on simplified statistical mechanical theories, the differences can be interpreted in terms of an increase in the configurational freedom of the palmitoyl chains in the polyunsaturated bilayer, relative to bilayers of phosphatidylcholines with two identical saturated chains. The increased configurational freedom may correspond to an increase in the equilibrium area per chain in the case of the polyunsaturated bilayer. Possible further interpretations of the results in terms of the thickness of the hydrocarbon region and the presence or lack of interdigitation of the polyunsaturated and saturated acyl chains are also briefly discussed. We conclude that the configurational properties of the acyl chains of polyunsaturated bilayers are significantly different from those of saturated phospholipid bilayers.",
author = "Amir Salmon and Dodd, {Steven W.} and Williams, {Gerald D.} and Beach, {James M.} and Brown, {Michael F}",
year = "1987",
language = "English (US)",
volume = "109",
pages = "2600--2609",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "9",

}

TY - JOUR

T1 - Configurational statistics of acyl chains in polyunsaturated lipid bilayers from 2H NMR

AU - Salmon, Amir

AU - Dodd, Steven W.

AU - Williams, Gerald D.

AU - Beach, James M.

AU - Brown, Michael F

PY - 1987

Y1 - 1987

N2 - To gain a better understanding of the biological roles of polyunsaturated phospholipids, deuterium (2H) NMR studies have been conducted of 1-perdeuteriopalmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, an asymmetric or mixed-chain saturated-polyunsaturated phospholipid, in the liquid crystalline (Lα) phase. The palmitoyl (16:0) chain at the glycerol sn-1 position was labeled with 2H by perdeuteration, whereas the polyunsaturated, docosahexaenoyl (22:6ω3) chain at the sn-2 position was unlabeled, i.e., protiated. The 2H NMR results were compared to studies of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which both the sn-1 and sn-2 palmitoyl chains were perdeuterated, as well as 1-palmitoyl-2-perdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which only the sn-2 chain was perdeuterated. Multilamellar phospholipid dispersions containing 50 wt % H2O were employed, and 2H NMR spectra were obtained using quadrupolar echo methods at a magnetic field strength of 8.5 T. The experimental 2H NMR spectra were numerically deconvolved (de-Paked) to yield subspectra corresponding to the parallel bilayer orientation with respect to the main applied magnetic field. The increased resolution of the de-Paked subspectra enabled profiles of the segmental order parameters of the individual C-2H bonds, denoted by |SCD(i)|, to be derived as a function of chain position. Significant differences in the 2H NMR spectra and derived |SCD(i)| profiles of the per-2H-16:0 chains of the polyunsaturated and saturated bilayers were found. Based on simplified statistical mechanical theories, the differences can be interpreted in terms of an increase in the configurational freedom of the palmitoyl chains in the polyunsaturated bilayer, relative to bilayers of phosphatidylcholines with two identical saturated chains. The increased configurational freedom may correspond to an increase in the equilibrium area per chain in the case of the polyunsaturated bilayer. Possible further interpretations of the results in terms of the thickness of the hydrocarbon region and the presence or lack of interdigitation of the polyunsaturated and saturated acyl chains are also briefly discussed. We conclude that the configurational properties of the acyl chains of polyunsaturated bilayers are significantly different from those of saturated phospholipid bilayers.

AB - To gain a better understanding of the biological roles of polyunsaturated phospholipids, deuterium (2H) NMR studies have been conducted of 1-perdeuteriopalmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine, an asymmetric or mixed-chain saturated-polyunsaturated phospholipid, in the liquid crystalline (Lα) phase. The palmitoyl (16:0) chain at the glycerol sn-1 position was labeled with 2H by perdeuteration, whereas the polyunsaturated, docosahexaenoyl (22:6ω3) chain at the sn-2 position was unlabeled, i.e., protiated. The 2H NMR results were compared to studies of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which both the sn-1 and sn-2 palmitoyl chains were perdeuterated, as well as 1-palmitoyl-2-perdeuteriopalmitoyl-sn-glycero-3-phosphocholine, in which only the sn-2 chain was perdeuterated. Multilamellar phospholipid dispersions containing 50 wt % H2O were employed, and 2H NMR spectra were obtained using quadrupolar echo methods at a magnetic field strength of 8.5 T. The experimental 2H NMR spectra were numerically deconvolved (de-Paked) to yield subspectra corresponding to the parallel bilayer orientation with respect to the main applied magnetic field. The increased resolution of the de-Paked subspectra enabled profiles of the segmental order parameters of the individual C-2H bonds, denoted by |SCD(i)|, to be derived as a function of chain position. Significant differences in the 2H NMR spectra and derived |SCD(i)| profiles of the per-2H-16:0 chains of the polyunsaturated and saturated bilayers were found. Based on simplified statistical mechanical theories, the differences can be interpreted in terms of an increase in the configurational freedom of the palmitoyl chains in the polyunsaturated bilayer, relative to bilayers of phosphatidylcholines with two identical saturated chains. The increased configurational freedom may correspond to an increase in the equilibrium area per chain in the case of the polyunsaturated bilayer. Possible further interpretations of the results in terms of the thickness of the hydrocarbon region and the presence or lack of interdigitation of the polyunsaturated and saturated acyl chains are also briefly discussed. We conclude that the configurational properties of the acyl chains of polyunsaturated bilayers are significantly different from those of saturated phospholipid bilayers.

UR - http://www.scopus.com/inward/record.url?scp=0000702940&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000702940&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0000702940

VL - 109

SP - 2600

EP - 2609

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 9

ER -