Carnitine acetyltransferase in pea cotyledon mitochondria |
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Authors: | N. Burgess D. R. Thomas |
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Affiliation: | (1) Department of Plant Biology, Newcastle University, NE1 7RU Newcastle-upon-Tyne, UK |
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Abstract: | Purified pea cotyledon mitochondria did not oxidise acetyl-CoA in the presence of carnitine. However, acetylcarnitine was oxidised. It was concluded that acetylcarnitine passed through the mitochondrial membrane barrier but acetyl-CoA did not. Only a sensitive radioactive assay detected carnitine acetyltransferase in intact mitochondrion or intact mitoplast preparations. When the mitochondria or mitoplasts were burst, acetyl-CoA substrate was available to the matrix carnitine acetyltransferase and a high activity of the enzyme was measured. The inner mitochondrial membrane is there-fore the membrane barrier to acetyl-CoA but acetylcarnitine is suggested to be transported through this membrane via an integral carnitine: acylcarnitine translocator. Evidence is presented to indicate that when the cotyledons from 48-h-grown peas are oxidising pyruvate, acetylcarnitine formed in the mitochondrial matrix by the action of matrix carnitine acetyltransferase may be transported to extra-mitochondrial sites via the membrane translocator. |
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Keywords: | Carnitine acetyltransferase (localization, function) Mitochondrion Pisum (carnitine acetyltransferase) |
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