Reorientational and conformational ordering processes at elevated pressures in 1,2-Dioleoyl phosphatidylcholine

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DOIResolve DOI: http://doi.org/10.1016/S0006-3495(88)83016-9
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TypeArticle
Journal titleBiophysical Journal
ISSN0006-3495
Volume54
Issue5
Pages781790
AbstractRaman and infrared spectra of fully hydrated bilayers of 1,2-dioleoyl phosphatidylcholine (DOPC) were measured at increasing hydrostatic pressures up to -37 kbar. Under ambient conditions aqueous dispersions of DOPC are in the liquid crystalline state. The application of an external hydrostatic pressure induces conformational and dynamic ordering processes in DOPC, which trigger a first-order structural phase transition at 5 kbar from a disordered liquid crystalline state to a highly ordered gel state. In the gel phase the methylene chains of each molecule are fully extended and the two all-trans chain segments on both sides of the rigid cis double bond form a bent structure. The bent oleoyl chains in each molecule, as well as in neighboring molecules are packed parallel to each other. To achieve this parallel interchain packing, the double bonds of the sn-1 and sn-2 chains of each molecule must be aligned at the same position with respect to the bilayer interface which is achieved by a rotation of the C—C bonds in the glycerol moiety in the head group. The extremely strong interchain interactions in the gel phase of DOPC are unique for this lipid with cis dimono-unsaturated acyl chains. Our experimental results suggest that in the pressure-induced gel phase of DOPC the olefinic CH bonds are rotated out of the phase of the bent oleoyl chains and that the oleoyl chains of opposing bilayers bend towards opposite directions.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada
Peer reviewedYes
NPARC number23001624
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Record identifierefbb7e26-d197-492c-842d-f973b7115c5d
Record created2017-03-13
Record modified2017-03-13
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