By A. Douglas Kinghorn, Heinz Falk, Simon Gibbons, Jun'ichi Kobayashi
The first contribution stories the prevalence of xanthine alkaloids within the plant nation and the elucidation of the caffeine biosynthesis pathway, supplying info of the N-methyltransferases, belonging to the motif B' methyltransferase kin which catalyze 3 steps within the 4 step pathway prime from xanthosine to caffeine. the second one contribution during this ebook offers a history at the molecule and comparable compounds and replace wisdom at the newest advances in Iboga alkaloids. The 3rd contribution provides a finished research of usually happening blunders with recognize to 13C NMR spectroscopic information and proposes an easy protocol to dispose of a excessive percent of the obvious errors.
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Additional resources for Progress in the Chemistry of Organic Natural Products 105
Sample text
For such a translocation, at least three membrane transport events would seemingly have to be involved, namely, export from the plasma membrane in root cells, import at the plasma membrane in leaf cells, and additional transport into the vacuoles in leaf cells [165]. In contrast to 47, long-distance transport of caffeine (8) has not yet been observed, although intracellular transport to vacuoles may occur. 1 43 Organs and Tissues Xanthine alkaloid biosynthetic activity in different organs and tissues was investigated from the 14C-feeding experiments, determination of enzyme activity and/or expression of caffeine synthase genes.
31-kb sequence of cDNA. The 50 untranslated sequence of the cDNA fragment was isolated by 50 -RACE. The isolated cDNA termed TCS1 [117] was expressed in Escherichia coli and the lysates of the bacterial cells incubated with a variety of xanthine substrates in the presence of SAM. The substrate specificity of the recombinant enzyme was similar to that of the native enzyme purified from young tea leaves [117]. The recombinant and native enzymes principally catalyze 3-N- and N-1-methylation of the purine ring of mono- and dimethylxanthines (Table 8).
169] reported that the caffeine synthase gene is expressed mainly in the palisade parenchyma and the epicuticle of tea leaves and less so in the spongy parenchyma and hypoderm. Coffea In coffee, biosynthetic activity has been detected in leaves and fruits. Transcript accumulation for the identified N-methyltransferase genes for caffeine biosynthesis was analyzed by the RT-PCR using gene-specific primer sets. The results indicated plural genes were expressed in different organs and tissues of coffee plants.