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Laurdan fluorescence spectroscopy in the thylakoid bilayer: The effect of violaxanthin to zeaxanthin conversion on the galactolipid dominated lipid environment

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Author

Summary, in English

Laurdan (6-lauroyl-2-dimethylaminonaphthalene) fluorescence spectroscopy has been applied to probe the physical status of the thylakoid membrane upon conversion of violaxanthin to zeaxanthin. So far, only phospholipid-dominated membranes have been studied by this method and hereby we report the first use of laurdan in mono- and digalactosyldiacylglycerol-dominated membrane systems. The generalised polarisation (GP) of laurdan was used as a measure of the structural effect of xanthophyll cycle pigments in isolated spinach (Spinacia oleracea) thylakoids and in model membrane vesicles composed of chloroplast galactolipids. Higher GP values indicate a membrane in a more ordered structure, whereas lower GP values point to a membrane in a less ordered fluid phase. The method was used to probe the effect of violaxanthin and zeaxanthin in thylakoid membranes at different temperatures. At 4, 25 and 37 degrees C the GP values for dark-adapted thylakoids in the violaxanthin-form were 0.55, 0.28 and 0.26. After conversion of violaxanthin to zeaxanthin, at the same temperatures, the GP values were 0.62, 0.36 and 0.34, respectively. GP values increased gradually upon conversion of violaxanthin to zeaxanthin. Similar results were obtained in the liposomal systems in the presence of these xanthophyll cycle pigments. We conclude from these results that the conversion of violaxanthin to zeaxanthin makes the thylakoid membrane more ordered.

Publishing year

2008

Language

English

Pages

348-355

Publication/Series

Biochimica et Biophysica Acta - Biomembranes

Volume

1778

Issue

1

Document type

Journal article

Publisher

Elsevier

Topic

  • Biological Sciences

Keywords

  • zeaxanthin
  • cycle
  • xanthophyll
  • galactolipids
  • thylakoid membrane
  • laurdan
  • fluorescence

Status

Published

ISBN/ISSN/Other

  • ISSN: 0005-2736