Palmitic and stearic acids bind Ca2+ with high affinity and form nonspecific channels in black-lipid membranes. Possible relation to Ca2+-activated mitochondrial pores

Galina D. Mironova, Odile Gateau-Roesch, Christiane Levrat, Elena Gritsenko, Evgeny Pavlov, Alissa V. Lazareva, Elena Limarenko, Catherine Rey, Pierre Louisot, Nils Erik L. Saris

Research output: Contribution to journalArticle

Abstract

A mitochondrial hydrophobic component that forms Ca2+-induced nonspecific ion channels in blacklipid membranes (Mironova et al., 1997) has been purified and its nature elucidated. It consists of long-chain saturated fatty acids-mainly palmitic and stearic. These fatty acids, similar to the mitochondrial hydrophobic component, bind Ca2+ with high affinity in comparison with unsaturated fatty acids, saturated fatty acids with shorter aliphatic chains, phospholipids, and other lipids. Ca2+binding is inhibited by Mg2+ but not by K+. For palmitic acid, the Kd for Ca2+ was 5 μM at pH 8.5 and 15 μM at pH 7.5, with the Bmax of 0.48 ± 0.08 mmol/g. This corresponds to one Ca2+ ion for eight palmitic acid molecules. The data of IR spectroscopy confirm that Ca2+ does not form ionic bonds with palmitic and stearic acids under hydrophobic conditions. It has been found that in the presence of Ca2+, palmitic and stearic acids, but not unsaturated FFA induce a nonspecific permeability in black-lipid membranes. Addition of Ca2+ in order to induce the permeability transition, increases the extractable amount of palmitic and stearic acids, the effect being prevented by a phospholipase A2 inhibitor. The possible involvement of palmitic and stearic acids in the mitochondrial nonspecific permeability is discussed.

Original languageEnglish (US)
Pages (from-to)319-331
Number of pages13
JournalJournal of Bioenergetics and Biomembranes
Volume33
Issue number4
DOIs
StatePublished - 2001

Keywords

  • Black-lipid membrane
  • Calcium binding
  • CsA-insensitive pore
  • Ion channel
  • Mitochondria
  • Palmitic acid
  • Phospholipase A

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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