Gas chromatographic analysis of free fatty acids of maize mitochondria under hypoxia

Abstract

Formation and metabolism of free fatty acids of mitochondria could characterize the condition of membrane phospholipid components and thus functioning of these organoids in different environment. Production of free fatty acids in mitochondria of maize seedlings under short-term (3-24h) hypoxic stress and CO₂-media was studied. Mitochondria was extracted by differential centrifugation method. Fraction purity was controlled by an enzyme of cytochrome oxidase. Method for extraction of free fatty acids from plant mitochondria by conversion into potassium salts and methylation by diazomethane has been developed. Gas- chromatographic analysis of fatty acid methyl esters showed the dominance of palmitic (С16:0) and linoleic (C18:2) acids with content of 14.65% and 20.75% respectively of total acids. Under hypoxia and especially under CO₂ there was an increase of palmitoleic (С16:1) and linoleic (C18:2) acids in maize seedlings. The noted changes of increase in unsaturation of free mono- and diene fatty acids in mitochondria were observed starting 9h of hypoxia and carbon dioxide media and till the end of experiment. This resulted in raised unsaturation (u/s) of free fatty acids of mitochondria from 1.14 to 1.21 and from 1.00 to 1.56 respectively. As- sumed, that phospholipid destruction of mitochondria membrane in plants under oxygen deficit could result in free fatty acid accumulation in this cell organoids. More significant changes in mitochondrial fund of free fatty acids were observed in plants exposed in CO₂-media. This proves the assumption that specific effect of carbon dioxide on plants is not only linked to its role of competitive inhibitor of enzymes but also because it involves changes in activity of several membrane-bound enzymes by affecting destruction of membrane phospholipids. Also, along with biochemical reorganization of mitochondrial membranes in seedlings under high concentrations of CO₂ there should be particular changes in their ultrastructure.