Molecular Dynamics of Vesicles of Unsaturated Phosphatidylcholines Studied by 13C NMR Spin-Lattice Relaxation

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Title:Molecular Dynamics of Vesicles of Unsaturated Phosphatidylcholines Studied by 13C NMR Spin-Lattice Relaxation
Creators:
Zajíček, Jaroslav
Ellena, Jeffrey F.
Williams, Gerald D.
Khadim, Mohammad A.
Brown, Michael F.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 60, 5, pp. 719-735

Abstract

<p><sup>13</sup>C spin-lattice relaxation times, <i>T</i><sub>1Z</sub>, were measured at four different magnetic field strengths for a vesicles of a series of unsaturated 1,2-diacyl-<i>sn</i>-glycero-3-phosphocholines over the temperature range from 5 to 50 °C. The acyl chains of the phosphatidylcholines varied in length from 14 to 18 carbons and in the degree of unsaturation: myristoleoyl (14 : 1), palmitoleoyl (16 : 1), oleoyl (18 : 1), linoleoyl (18 : 2), linolenoyl (18 : 3). For each of the phosphatidylcholines studied the <i>R</i><sub>1Z</sub> = (<i>NT</i><sub>1Z</sub>)<sup>-1</sup> values of the acyl chain methylene carbons, where <i>N</i> is the number of directly bonded hydrogens, decreased from the C<sub>2</sub> position which is situated close to the glycerol backbone towards the acyl terminal methyl group. The effect of the double bond was manifested by an increase in <i>R</i><sub>1Z</sub> and was less pronounced if it was located closer to the terminal methyl group than in the middle of the chain. A minimum in the <i>T</i><sub>1Z</sub> relaxation times was not observed, even for highest frequency of 125.8 MHz and the lowest temperature of 5 °C. In the case of the phosphocholine headgroup and glycerol backbone carbons the <i>T</i><sub>1Z</sub> times showed similar temperature and frequency dependencies as the acyl chain carbons. The results of the measurements indicate substantial differences in the dynamics of these systems in the liquid-crystalline state. Analysis of the data using various dynamical models is consistent with a distribution of motions which is not described by a single Lorentzian spectral density. This dispersion appears to be an inherent feature of the dynamics of phosphatidylcholines in the liquid-crystalline state.

Title:Molecular Dynamics of Vesicles of Unsaturated Phosphatidylcholines Studied by 13C NMR Spin-Lattice Relaxation
Creators:
Zajíček, Jaroslav
Ellena, Jeffrey F.
Williams, Gerald D.
Khadim, Mohammad A.
Brown, Michael F.
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:60
Number:5
Page Range:pp. 719-735
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19950719UNSPECIFIED
ID Code:763
Item Type:Article
Deposited On:06 Feb 2009 17:03
Last Modified:06 Feb 2009 16:03

Citation

Zajíček, Jaroslav; Ellena, Jeffrey F.; Williams, Gerald D.; Khadim, Mohammad A.; Brown, Michael F. (1995) Molecular Dynamics of Vesicles of Unsaturated Phosphatidylcholines Studied by 13C NMR Spin-Lattice Relaxation. Collection of Czechoslovak Chemical Communications, 60 (5). pp. 719-735. ISSN 0010-0765

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