Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Diterpenes taxadienes

To date over 30 plant terpenoid synthases have been cloned as cDNAs, and many of these were found to encode enzymes of secondary metabolism (43). Isolation and analysis of six genomic clones encoding monoterpene ((—)-pinene and (—)-limonene), sesquiterpene ((E)-a-bisabolene and S-selinene) and diterpene (abietadiene) synthases from Abies grandis, and a diterpene (taxadiene) synthase from Taxus brevifolia have been reported (44). Overexpression of a cotton farnesyl diphosphate synthase (EPPS) in transgenic Artemesia annua has resulted in 3- to 4-fold increase in the yield of the sesquiterpenoid anti-malarial drug, artemisinin, in hairy roots (45). [Pg.490]

In plant plastids, GGPP is formed from products of glycolysis and is eight enzymatic steps away from central glucose metabolism. The MEP pathway (reviewed in recent literature - ) operates in plastids in plants and is a preferred source (non-mevalonate) of phosphate-activated prenyl units (IPPs) for plastid iso-prenoid accumulation, such as the phytol tail of chlorophyll, the backbones of carotenoids, and the cores of monoterpenes such as menthol, hnalool, and iridoids, diterpenes such as taxadiene, and the side chains of bioactive prenylated terpenophe-nolics such as humulone, lupulone, and xanthohumol. The mevalonic pathway to IPP that operates in the cytoplasm is the source of the carbon chains in isoprenes such as the polyisoprene, rubber, and the sesquiterpenes such as caryophyllene. [Pg.360]

By using an elegant 13C-labeling study that involved incubation of Phoma sp. with 1-13C and 1,2-13C acetate, Oikawa et al. [9], were able to isolate the proposed biosynthetic intermediate phomactatriene (or Sch 49026), with 13C incorporation from singly labeled acetate units as indicated by in Fig. 8.3. Phomactatriene is strikingly reminiscent of taxadiene, a biosynthetic intermediate for Taxol . The net biosynthesis for both involves geranylgeranyl diphosphate (GGDP) cyclization [9]. It is noteworthy that prior to isolation of phomactins, the only known related structure is cleomeolide, a diterpene from the herb Cleome viscosa [10] that remarkably resembles phomactin H. [Pg.185]

The metabolism of taxol by Eucalyptus perriniana cell suspension cultures has been recently reported to induce hydrolyses of ester bonds at C-13, C-10 and C-2 [222]. At this moment only very few data have been published about the microbial metabolism of taxoid compounds only site specific hydrolyses of acyl side-chains at C-13 or C-10 by extracellular and intracellular esterases of Nocar-dioides albus SC13,911 and N. luteus SC13,912, respectively, have been reported [223]. On the other hand, Hu et al. [224-226] have recently described some fungal biotransformations of related natural taxane diterpenes extracted from Chinese yews or their cell cultures, in order to obtain new active substances or precursors for hemisynthesis. The taxadiene 145, a 14 -acetylated derivative... [Pg.209]

WILLIAMS, D. C., WILDUNG, M. R., JIN, A. Q. W., DALAL, D., OLIVER, J. S., COATES, R. M., CROTEAU, R., Heterologous expression and characterization of a "pseudomature" form of taxadiene synthase involved in paclitaxel (Taxol) biosynthesis and evaluation of a potential intermediate and inhibitors of the multistep diterpene cyclization reaction, Arch. Biochem. Biophys., 2000, 379, 137-146. [Pg.250]

Wildung, M.R. and Croteau, R. (1996) A cDNA clone for taxadiene synthase, the diterpene cyclase that catalyzes the committed step of taxol biosynthesis. /. Biol. Chem., 271, 9201-4. [Pg.302]

Wildung MR, Croteau R (1996) A cDNA Clone for Taxadiene Synthase, the Diterpene Cyclase That Catalyzes the Committed Step of Taxol Biosynthesis. J Biol Chem 271 9201... [Pg.224]

The abietadiene synthase from fir was purified and internal amino-acid sequence information was employed to isolate the corresponding clone from a wound-induced stem cDNA library [147]. The cDNA encodes an 868 residue protein (99,536 Da) bearing a plastidial transit peptide and exhibiting the greatest sequence similarity to the only other known gymnosperm diterpene cyclase, taxadiene synthase from Taxus brevifolia [130]. Preliminary studies have identified a highly active truncation starting at V85 which approximates the preprotein-mature protein junction. [Pg.87]

The diterpene taxol from Pacific yew is one of the most powerful anticancer agents in therapeutic use today. In a series of seminal discoveries, the group of Croteau has dissected the pathway to this complex molecule at the enzymatic and molecular genetic levels, leading to recent success in partial reconstmction of the pathway in yeast [33]. The diterpene synthase taxadiene synthase catalyzes the cyclization of GGPP as the first committed step in taxol formation [34]. [Pg.150]

A series of ionization and proton-induced cycUzations 16 20 catalyzed by the taxadiene synthase convert GGPP 1 into the taxadienes 21 and 22 for en mute synthesis of biological important natural products such as taxol and analogs (Scheme 8.2) [7]. Abietanes andkauranes are important classes of diterpenes. In the presence of abietadiene synthase, 1 undergoes a proton-induced cascade cyclization to produce the copalyl diphosphate intermediate 23 (Scheme 8.2) [8]. The latter is converted to 24 via an ionic cyclization and then to 25 through a methyl 1,2-shift between C13 and C14 [9]. In contrast, diterpene mt-kaur-16-ene 29 is not formed via the same cyclase enzyme. Consequently, it was proposed that two enzymes, mt-copalyl diphosphate and cnt-kaurene... [Pg.279]


See other pages where Diterpenes taxadienes is mentioned: [Pg.203]    [Pg.411]    [Pg.317]    [Pg.203]    [Pg.411]    [Pg.317]    [Pg.280]    [Pg.151]    [Pg.64]    [Pg.64]    [Pg.151]    [Pg.398]    [Pg.356]    [Pg.491]    [Pg.1103]    [Pg.2718]    [Pg.80]    [Pg.454]    [Pg.67]    [Pg.69]    [Pg.314]    [Pg.279]   
See also in sourсe #XX -- [ Pg.279 , Pg.281 ]




SEARCH



Diterpenes

Taxadiene

© 2024 chempedia.info