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On the localization of ubiquinone in phosphatidylcholine bilayers.

Publication ,  Journal Article
Stidham, MA; McIntosh, TJ; Siedow, JN
Published in: Biochim Biophys Acta
December 18, 1984

The location of ubiquinone-10 in phospholipid bilayers was analyzed using a variety of physical techniques. Specifically, we examined the hypothesis that ubiquinone localizes at the geometric center of phospholipid bilayers. Light microscopy of dipalmitoylphosphatidylcholine at room temperature in the presence of 0.05-0.5 mol fraction ubiquinone showed two separate phases, one birefringent lamellar phase and one phase that consisted of isotropic liquid droplets. The isotropic phase had a distinct yellow color, characteristic of melted ubiquinone. [13C]NMR spectroscopy of phosphatidylcholine liposomes containing added ubiquinone indicated a marked effect on the 13C-spin lattice relaxation times of the lipid hydrocarbon chain atoms near the polar head region of the bilayer, but almost no effect on those atoms nearest the center of the bilayer. X-ray diffraction experiments showed that for phosphatidylcholine bilayers, both in the gel and liquid-crystal-line phases, the presence of ubiquinone did not change either the lamellar repeat period or the wide-angle reflections from the lipid hydrocarbon chains. In electron micrographs, the hydrophobic freeze-fracture surfaces of bilayers in the rippled (P beta') phase were also unmodified by the presence of ubiquinone. These results indicate that the ubiquinone which does partition into the bilayer is not localized preferentially between the monolayers, and that an appreciable fraction of the ubiquinone forms a separate phase located outside the lipid bilayer.

Duke Scholars

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

December 18, 1984

Volume

767

Issue

3

Start / End Page

423 / 431

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Ubiquinone
  • Phosphatidylcholines
  • Microscopy, Electron
  • Magnetic Resonance Spectroscopy
  • Lipid Bilayers
  • Freeze Fracturing
  • 06 Biological Sciences
  • 02 Physical Sciences
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Stidham, M. A., McIntosh, T. J., & Siedow, J. N. (1984). On the localization of ubiquinone in phosphatidylcholine bilayers. Biochim Biophys Acta, 767(3), 423–431. https://doi.org/10.1016/0005-2728(84)90040-9
Stidham, M. A., T. J. McIntosh, and J. N. Siedow. “On the localization of ubiquinone in phosphatidylcholine bilayers.Biochim Biophys Acta 767, no. 3 (December 18, 1984): 423–31. https://doi.org/10.1016/0005-2728(84)90040-9.
Stidham MA, McIntosh TJ, Siedow JN. On the localization of ubiquinone in phosphatidylcholine bilayers. Biochim Biophys Acta. 1984 Dec 18;767(3):423–31.
Stidham, M. A., et al. “On the localization of ubiquinone in phosphatidylcholine bilayers.Biochim Biophys Acta, vol. 767, no. 3, Dec. 1984, pp. 423–31. Pubmed, doi:10.1016/0005-2728(84)90040-9.
Stidham MA, McIntosh TJ, Siedow JN. On the localization of ubiquinone in phosphatidylcholine bilayers. Biochim Biophys Acta. 1984 Dec 18;767(3):423–431.

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

December 18, 1984

Volume

767

Issue

3

Start / End Page

423 / 431

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Ubiquinone
  • Phosphatidylcholines
  • Microscopy, Electron
  • Magnetic Resonance Spectroscopy
  • Lipid Bilayers
  • Freeze Fracturing
  • 06 Biological Sciences
  • 02 Physical Sciences