| | 3 | Author
| Dieter Strack | Requires cookie* | | | Title
| Sinapine as a Supply of Choline for the Biosynthesis of Phosphatidylcholine in Raphanus sativus Seedlings  | | | | Abstract
| Biosynthesis o f phosphatidylcholine in young seedlings o f Raphanus sativus is supplied with choline from degradation of the seed constituent sinapine (sinapoylcholine). This conclusion has been deduced from the following results: (1) Raphanus sativus seedlings accumulate approx. 70 nmol phosphatidylcholine which may be relevant for the consumption of choline, liberated during hydrolysis of approx. 130 nmol sinapine. (2) [14C]choline and [14C]ethanolamine, taken up by germinating Raphanus seeds, are exclu sively consumed in the biosynthesis o f phosphatidylcholine and phosphatidylethanolamine, respectively. (3) Pulse-chase experiments with seedlings at different germination stages show a reduced [14C]choline incorporation into phosphatidylcholine at the time when degradation o f sinapine occurs, obviously as a result of an isotope dilution by an increase o f the endogenous choline pool. (4) After [14C]choline pulse to immature seeds, during the process o f seed maturation most of the activity taken up is incorporated into accumulating sinapine and approx. 50% compared to this into phosphatidylcholine. During seedling development the quantity o f labelled sinapine rapidly decreases as a result of sinapine degradation with a concomitant label increase in free choline, phosphorylcholine, and phosphatidylcholine. Approx. 50% of the choline liberated from sinapine, is consumed in the biosynthesis of phosphatidylcholine. High performance liquid chromatographic analyses of phosphatidylcholine during Raphanus germination revealed that this phospholipid might be a metabolically active compound. Changes in the absorptivity of this compound at 210 nm indicate changes in the degree of unsaturation in the fatty acyl groups. | | | |
Reference
| Z. Naturforsch. 36c, 215—221 (1981); received December 231980 | | | |
Published
| 1981 | | | |
Keywords
| Sinapine, Phosphatidylcholine, Phenylpropanoids, Phospholipids, Raphanus, Brassicaceae | | | |
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| default:Reihe_C/36/ZNC-1981-36c-0215.pdf | | | | Identifier
| ZNC-1981-36c-0215 | | | | Volume
| 36 | |
| 4 | Author
| G. Erhild, N. Urm, Ann, D. Ieter Strack | Requires cookie* | | | Title
| Sinapine Esterase I. Characterization of Sinapine Esterase from Cotyledons of Raphanus sativus | | | | Abstract
| From cotyledons o f Raphanus sativus (red radish) an esterase activity which catalyzes the hy drolysis o f sinapine into sinapic acid and choline has been isolated. The enzyme, which has a near absolute specificity, is not analogous with any esterase described in the literature. The reaction has a pH optim um o f 8.5 and the apparent K m is 1.95 x 10~5 m. The enzyme is relatively insensi tive to both physostigm ine (eserine) {K x = 1.73 x 10-4 m) and neostigm ine (A'i = 2 .1 3 x 10-4 m). Diisopropyl fluorophosphate (D F P) showed no inhibition and diethyl /?-nitrophenylphosphate (E 600) only a slight inhibitory effect at 10-5 m, respectively. Choline (10~2 m) was inhibitory but acetylcholine (1 0 -2 m) stimulated the enzyme activity. | | | |
Reference
| Z. Naturforsch. 34c, 715—720 (1979); received June 11 1979 | | | |
Published
| 1979 | | | |
Keywords
| Esterase, Sinapine, Sinapic Acid Esters, Raphanus, Brassicaceae, High-Performance Liquid Chro matography (HPLC) | | | |
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| default:Reihe_C/34/ZNC-1979-34c-0715.pdf | | | | Identifier
| ZNC-1979-34c-0715 | | | | Volume
| 34 | |
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