Homogeneous catalytic hydrogenation of lipids in the photosynthetic membrane: Effects on membrane structure and photosynthetic activity

Gábor Horváth, Magdolna Droppa, Tatiana Szitó, LászlóA A. Mustárdy, LászlóI I. Horváth, László Vigh

Research output: Contribution to journalArticle

18 Citations (Scopus)


We have carried out a series of experiments in which the lipid composition of the photosynthetic membrane has been altered by the homogeneous catalytic hydrogenation of the unsaturated fatty acid residues of membrane lipids. The modified membrane was investigated by electron microscopy, electron-spin resonance and fluorescence polarization methods. Alteration in the functional characteristics of the hydrogenated membrane was monitored by the measurement of photophosphorylation and electron-transport activities. The following results were found. (a) Saturation of 10% of the fatty acyl double bonds induced a definite decrease in the dimension of both thylakoids and loculi. Microdensitometry showed that these structural changes arose from a thickening of the single membranes with a simultaneous decrease in the spacing between membranes. These changes might be accounted for by the alignment of the hydrocarbon chains of saturated lipids and the increased hydrophobicity of the membranes. (b) The orientational pattern of chlorophyll-a molecules was not altered by saturating up to 50% of fatty acyl double bonds in membrane lipids, indicating that the energy-transfer processes amongst the chlorophyll molecules remained functional after hydrogenation. (c) Saturation of double bonds of lipids inhibited whole electron transport prior to the inhibition of Photosystem II and Photosystem I activity, which may suggest that the unsaturation level of fatty acids plays a crucial role by ensuring the lateral mobility of plastoquinone between Photosystem II and Photosystem I.

Original languageEnglish
Pages (from-to)325-336
Number of pages12
JournalBBA - Bioenergetics
Issue number3
Publication statusPublished - May 16 1986



  • (Pea chloroplast)
  • Chloroplast membrane
  • Electron transport
  • Lipid hydrogenation
  • Membrane fluidity
  • Photophosphorylation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this