Intramembraneous hydrogenation of mitochondrial lipids reduces the substrate availability, but not the enzyme activity of endogenous phospholipase A. The role of polyunsaturated phospholipid species

Michael Schlame, Ibolya Horvath, Zsolt Török, Laszlo I. Horvath, Laszlo Vigh

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22 Citations (Scopus)

Abstract

(1) Isolated rat liver mitochondria were subjected to catalytic hydrogenation using a water-soluble Pd complex and molecular H2. This treatment resulted in a reduction of double bonds on phospholipid acyl chains as judged by gas chromatography of fatty acid methyl esters and HPLC of dinitrobenzoyldiacylglycerols. (2) After hydrogenation, mitochondria lost their ability to hydrolyze endogenous phospholipids in alkaline, Ca2+ containing medium, while phospholipase A2 retained full activity against exogenous substrates, regardless of whether those substrates were hydrogenated or not. (3) Inhibition by hydrogenation of endogenous phospholipid hydrolysis correlated with the loss of polyunsaturated fatty acyls, rather than with changes of the bulk membrane fluidity as measured by ESR and fluorescence studies. (4) These data suggest that the unsaturation of mitochondrial membrane lipids might be important for regulation of phospholipid breakdown by endogenous phospholipases. In particular, polyunsaturated molecular species seem to be involved in making phospholipids accessible to phospholipase A-mediated hydrolysis.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Volume1045
Issue number1
DOIs
Publication statusPublished - Jun 28 1990

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Keywords

  • (Rat liver mitochondria)
  • Membrane fluidity
  • Phospholipase A
  • Phospholipid acyl species
  • Polyunsaturated fatty acid

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Endocrinology

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