The subcellular distribution and biosynthesis of castaprenols and plastoquinone in the leaves of Aesculus hippocastanum |
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| Authors: | A R Wellburn and F W Hemming |
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| Affiliation: | Department of Biochemistry, University of Liverpool |
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| Abstract: | Intact chloroplasts and cell walls were prepared from horse-chestnut leaves that had previously metabolized 2-(14)C]mevalonate. The bulk of the castaprenols and plastoquinone-9 was found within the chloroplasts. The remaining portion of the castaprenols was associated with the cell-wall preparation whereas that of the plastoquinone-9 was probably localized in the soluble fraction of the plant cell. The (14)C content of these compounds of different cell fractions indicated the presence of polyisoprenoid-synthesizing activity both inside and outside the chloroplasts. This was confirmed by the relative incorporation of (14)C when ultrasonically treated and intact chloroplasts were incubated with 2-(14)C]mevalonate. As the leaves aged (on the tree) an increase in extraplastidic castaprenols and plastoquinone-9, together with associated synthesizing activities, was observed. |
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