Effects of glucose starvation on the oxidation of fatty acids by maize root tip mitochondria and peroxisomes: evidence for mitochondrial fatty acid beta-oxidation and acyl-CoA dehydrogenase activity in a higher plant
| Autor: | Ivan Couée, Alain Pradet, M. Dieuaide, Philippe Raymond |
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| Rok vydání: | 1993 |
| Předmět: |
Radioisotope Dilution Technique
Palmitic Acid Dehydrogenase Palmitic Acids Biology Mitochondrion Cell Fractionation Biochemistry Microbodies Zea mays Acyl-CoA Dehydrogenase Palmitic acid chemistry.chemical_compound Acyl-CoA Dehydrogenases Acetyl Coenzyme A Centrifugation Density Gradient Coenzyme A Carbon Radioisotopes Molecular Biology Beta oxidation Chromatography High Pressure Liquid chemistry.chemical_classification Acyl CoA dehydrogenase Fatty acid Cell Biology Peroxisome Mitochondria Citric acid cycle Glucose chemistry biology.protein Caprylates Oxidation-Reduction Research Article |
| Zdroj: | The Biochemical journal. 296 |
| ISSN: | 0264-6021 |
| Popis: | Fatty acid beta-oxidation was studied in organellar fractions from maize root tips by h.p.l.c. and radiometric analysis of the products of incubations with [1-14C]octanoate and [1-14C]palmitate. In crude organellar fractions containing both mitochondria and peroxisomes, octanoate and palmitate beta-oxidation, as determined by the production of acetyl-CoA, was functional and, for palmitate, was activated 4-12-fold after subjecting the root tips to 48 h of glucose starvation. The sensitivity to a ‘cocktail’ of respiratory-chain inhibitors containing cyanide, azide and salicylhydroxamate depended on the conditions of incubation, with no inhibition in a medium facilitating peroxisomal beta-oxidation and a significant inhibition in a medium potentially facilitating mitochondrial beta-oxidation. Indeed, preparations of highly purified mitochondria from glucose-starved root tips were able to oxidize octanoate and palmitate to give organic acids of the tricarboxylic acid cycle. This activity was inhibited 5-10-fold by the above cocktail of respiratory-chain inhibitors, with no parallel accumulation of acetyl-CoA, thus showing that the inhibition affected beta-oxidation rather than the pathway from acetyl-CoA to the organic acids. This provides the first evidence that the complete beta-oxidation pathway from fatty acids to citrate was functional in mitochondria from a higher plant. Moreover, an acyl-CoA dehydrogenase activity was shown to be present in the purified mitochondria. In contrast with the peroxisomal activity, mitochondrial beta-oxidation showed the same efficiency with octanoate and palmitate and was strictly dependent on glucose starvation. |
| Databáze: | OpenAIRE |
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