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Pea mitochondrial lipids and their oxidation during mitochondria swelling
Author(s) -
Haydar M.,
Hadziyev D.
Publication year - 1974
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740251012
Subject(s) - phosphatidylethanolamine , degree of unsaturation , phosphatidylcholine , mitochondrion , swelling , chemistry , biochemistry , cardiolipin , ascorbic acid , phospholipid , linoleic acid , palmitic acid , oleic acid , fatty acid , chromatography , food science , membrane , chemical engineering , engineering
The composition and oxidation of lipids in pea mitochondria induced by swelling in presence of some transitional metal ions and ascorbic acid has been studied. Among the major mitochondrial lipids found were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and diphosphatidylglycerol. The major fatty acids present in these lipids were linoleic, oleic and palmitic acids. The average unsaturation for mitochondria total fatty acids, expressed as Double Bond Index was 1.44, while the unsaturation for fatty acids of individual lipids varied between 1.02 and 1.73 being highest for an unidentified phospholipid and 1.44 for phosphatidylcholine present in mitochondria as the major lipid. Mitochondria isolated from pea seeds germinated for 4 days were found to be tightly coupled and to have an ADP/O ratio of 1.3. The swelling assay in 0.1 M‐KCl for 1‐day‐old mitochondria has shown a swelling ability matching those of 4 and up to 8 days of age. Isolated mitochondria aged for 24 h at 2–4º C showed a swelling comparable to that of the fresh preparation. Swelling in the presence of ascorbic acid did not induce mitochondrial lipid oxidation. However, this was brought about in the presence of Cu 2+ ions. The presence of Fe 2+ ions induced the highest degree of oxidation, and instead of a concurrent swelling, it induced contraction. At the same level of ions, Fe 2+ was more effective than Fe 3+ . Contrary to iron used at 4% of its physiological level, Mn 2+ and Co 2+ used at 12 to 24% of their levels found in pea seeds were ineffective in inducing oxidation. Nevertheless, the degree of mitochondrial swelling was highest in the medium containing KCl, lower in the presence of Co 2+ and ascorbic acid and lowest in the presence of Fe 3+ . These results suggested that mitochondrial lipid oxidation does not depend on the degree of swelling. The lipid peroxides formed within mitochondria, up to 8 mg of mitochondrial protein, could not be detected by dropping mercury electrode polarography but were readily determined colorimetrically using thiobarbituric acid reagent.