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1988 (2)
1982 (1)
1Author    P. A. Bäumker, S. Arendt, R. WiermannRequires cookie*
 Title    Metabolism of Ferulic Acid Sucrose Esters in Anthers of Tulipa cv. Apeldoorn: I. The Accumulation of Esters and Free Sugars  
 Abstract    The authors of Tulipa cv. Apeldoorn accumulate a large amount of ferulic acid sucrose esters. In addition to the well-known diferuloyl-(DFS) and triferuloyl sucrose esters (TFS), a new phenylpropanoid characterized as a monoester of ferulic acid and sucrose is described. Like TFS and DFS, this ester exhibits an accumulation maximum in the early stages of pollen development. Numerous free sugars have been extracted from Tulipa anthers. Three of them were identified as sucrose, glucose and fructose. Sucrose as the main component is accumulated in extremely high amounts during specific developmental stages (= 20% of the dry weight). After separation of the anthers into an anther wall fraction (AWF) and pollentapetum (PTF), each fraction shows a different accumulation kinetic of the free sugars and the ferulic acid esters. A correlation could be observed between the occurrence of the esters and sucrose in the pollen-tapetum fraction during the anther development. 
  Reference    Z. Naturforsch. 43c, 641—646 (1988); received May 16 1988 
  Published    1988 
  Keywords    Tulipa cv Apeldoorn, Anthers, Ferulic Sucrose Esters, Free Sugars 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0641.pdf 
 Identifier    ZNC-1988-43c-0641 
 Volume    43 
2Author    G. Kleinehollenhorst, H. Behrens, G. Pegels, N. Srunk, R. W. Ierm AnnRequires cookie*
 Title    Formation of Flavonol 3-O-Diglycosides and Flavonol 3-O-Trigly- cosides by Enzyme Extracts from Anthers of Tulipa cv. Apeldoorn Characterization and Activity o f Three D ifferent O -Glycosyltransferases during Anther Development  
 Abstract    Three distinct glycosyltransferases have been isolated and partially purified from anthers o f Tulipa cv. Apeldoorn. The following designations are proposed; UDP-glucose: flavonol 3-O-glu-cosyltransferase (GT-I), UDP-rhamnose: flavonol 3-O-glucoside rhamnosyltransferase (GT-II) and UDP-xylose: flavonol 3-glycoside xylosyltransferase (GT-III). The three enzymes exhibited an identical pH optimum within the range o f 8.5 —9.0. The estimated molecular weight of GT-I and GT-II was about 40 000, GT-III showed a molecular weight o f 30 000. GT-III required ions like NH^or Ca2+ whereas these ions have almost no influence on GT-I and GT-II activity. The en­ zymes have a slight requirement for SH-reagents, particularly DTE. As opposed to GT-II activity of GT-I and GT-III is significantly influenced by SH reagents and PCMB. Sucrose enhanced GT-III activity but only slightly GT-I activity, GT-II activity is not influenced. Flavonol aglycones can function as glycosyl acceptor for the GT-I, whereas flavonol 3-O-gly-cosides, luteolin, dihydroquercetin, naringenin, cyanidin, /»-coumaric acid and some other phenols were inactive as acceptor. The best acceptors were isorhamnetin and quercetin (Km: 0.9x10~6 m). GT-II did not accept aglycones as substrates. For this enzyme flavonol 3-O-glu-cosides were the most attractive substrates. GT-III did not have any affinity towards aglycones, too. This enzyme exhibited a high specificity for flavonol 3-O-glucosides as well as flavonol 3-0-galactosides. Both enzymes, the GT-II and GT-III, were able to glycosylate flavonol 3-O-digly-cosides forming triglycosides. UDP-glucose (K m= l.OxlO-4 m), UDP-rhamnose and UDP-xylose where shown to be the best glycosyl donors for GT-I, GT-II or GT-III respectively. The glycosyl transfer catalysed by the GT-I was shown to be a freely reversible reaction. In the whole anthers, highest specific activities o f GT-I and GT-II were found during late stages of anther development. Similar results were obtained using the contents o f anthers or the tapetum fraction. In contrary, high GT-III activity can be detected already in young stages o f anther devel­ opment. The highest activities o f the three glycosyltransferases were found in the tapetum frac­ tion, whereas the pollen fraction exhibited only poor activities. 
  Reference    Z. Naturforsch. 37c, 587—599 (1982); received March 18 1982 
  Published    1982 
  Keywords    Liliaceae, Tulipa cv Apeldoorn, Anthers, Flavonoid Metabolism, Enzymatic, O-Glycosyltransferase 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0587.pdf 
 Identifier    ZNC-1982-37c-0587 
 Volume    37 
3Author    P. A. Bäumker, S. Arendt, R. WiermannRequires cookie*
 Title    Metabolism of Ferulic Acid Sucrose Esters in Anthers of Tulipa cv. Apeldoorn: II. Highly Specific Degradation of the Esters by Different Esterase Activities  
 Abstract    Protein extracts from anthers of Tulipa cv. Apeldoorn catalyze the degradation of ferulic acid sucrose esters. Different products are generated when triferuloyl sucrose (TFS) and diferuloyl sucrose (DFS) were applied as substrates. By the aid of reversed-phase HPLC, TLC and spectro-scopy the products could be identified as free ferulic acid, monoferuloyl sucrose ester [feruloyl-sucrose(mono)] and two different diesters of ferulic acid and sucrose [feruloylsucrose(di) and the endogenously occurring diferuloylsucrose (DFS)]. By means of protein fractionation (chromatofocusing, anion exchange HPLC and molecular sieving HPLC), four different enzyme activities involved in the degradation process could be separated. According to their catalytic properties, they were characterized as esterases (= EA). The partially purified esterase activity I (EA I) obtained after fractionation by chromatofocus-ing catalyzes the formation of feruloylsucrose(di) and ferulic acid when TFS is used as substrate. Incubations with EA la or EA lb isolated in smaller portions lead to the same product pattern. The esterase activity II (EA II) degrades TFS to ferulic acid and DFS. DFS as substrate is only accepted by the EA I activities, in all three cases ferulic acid and feruloyl sucrose(mono) are formed as products. The kinds of different degradation reactions clearly indicate that one enzyme (= the EA II activity) catalyzes exclusively the formation of DFS from TFS. Both enzymes, EA I and EA II, exhibit a high specificity towards ferulic acid sucrose esters. Hydroxycinnamic sucrose esters with only sinapic acid moieties do not function as substrates. When enzymatically formed sucrose esters like feruloylsucrose(di), feruloylsucrose(mono) and mono-sinapoylsucrose were used as substrates, no product formation could be observed. Applying SFS as substrate, only the ferulic acid moiety was released by EA I. Further, naturally occurring esters (glucose-and CoA-esters of p-coumaric, caffeic, ferulic and sinapic acid; chlorogenic acid; BGM) tested so far were not degraded by EA I and EA II. It is assumed that these esterase activities play a specific role in the ferulic acid metabolism in Tulipa anthers. 
  Reference    Z. Naturforsch. 43c, 647—655 (1988); received May 16 1988 
  Published    1988 
  Keywords    Tulipa cv Apeldoorn, Anthers, Ferulic Acid Sucrose Esters, Degradation, Esterases 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0647.pdf 
 Identifier    ZNC-1988-43c-0647 
 Volume    43