The biosynthesis of shikimate metabolites

The biosynthesis of shikimate metabolites

“…The benzoic acid portion of the tropane alkaloid cocaine (61) from the coca plant (Erythroxylum coca) is known to be derived from phenylalanine (see Ref. 97), and chain shortening of cinnamic acid (62) via P-oxidation has generally been assumed to be operative. In recent studies, cinnamic acid and its N-acetylcysteamine thioester were shown to be specific precursors of the benzoyl moiety of cocaine, and 3-hydroxy-3-phenylpropanoic acid was also well i n ~o r p o r a t e d .…”

“…The stereoselective formation of ( -)-secoisolariciresinol (75) from coniferyl alcohol in cell-free extracts of Forsythia intermedia had been shown to require H,02 and NADPH as cofactors (see Ref. 97). Further investigation has shown that pinoresinol also accumulated in the soluble cell-free assay mixture with the (-)-isomer present in more than 96% enantiomeric excess.134 Initially, both (+)-and (-)-enantiomers of pinoresinol were formed, but the (+)-isomer was then rapidly lost.…”

“…A flavonol3-sulfotransferase activity from Flaveria chloraefolia catalysing the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the 3-hydroxyl of flavonol aglycones has been purified and chara~terized. '~~ The enzyme was specific for position 3 of flavonols, with the methylated flavonols rhamnetin (106) and isorhamnetin (107) more effective substrates than quercetin (97) or kaempferol (96). In further studies,150 cDNA clones coding for two flavonol sulfotransferases were isolated, sequenced, and expressed in E. coli, leading to P-galactosidase-sulfotransferase fusion proteins.…”