Enzymic glucosylation of gibberellins |
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Authors: | H. -D. Knö fel, E. Schwarzkopf, P. Mü ller G. Sembdner |
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Affiliation: | (1) Institute of Plant Biochemistry, Halle (Saale), GDR;(2) Research Centre for Molecular Biology and Medicine, Academy of Sciences of the German Democratic Republic, GDR |
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Abstract: | Starting from the well-known conversion of exogenously applied free gibberellic acid (GA3) to its 3(O)-glucoside by intact immature fruits of runner beans (Phaseolus coccineus L.), a protein fraction has been prepared from this plant material possessing glucosylating activity towards GAs. This glucosyltransferase is located in the pericarp only and utilizes preferably UDP-glucose as a sugar donor. The product formed enzymically from GA3 and UDP-glucose could be identified by derivatization and comparison with the authentic compound to be GA3-3(O)-glucoside. Among 15 native or chemically modified GAs, the enzyme glucosylates only GA3 and to a lower extent GA7 and GA30, indicating a high enzyme specificity with regard to the A ring of gibberellins. The physiological significance of the enzymic GA3-3(O)-glucoside formation inPhaseolus coccineus is not clear, since this glucoside is not known to be endogenous in this plant. The enzyme preparation did not glucosylate substances of phenolic structure, such as hydroquinone, aesculetin, and quercetin. Glucosylation of GA3 was achieved also by enzyme preparations fromVigna sinensis and from cell suspension cultures ofDigitalis purpurea. A number of other plant materials showed no activity.Gibberellins 100. For part 99 see Liebisch et al. 1984a. |
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