- NEUE SESQUITERPENLACTONE AUS ASTER UMBELLATUS
-
The investigation of Aster umbellatus afforded six new eudesmanolides and a new selina-triene and from Aster exilis a new tremetone derivative was isolated.The structures were elucidated by spectroscopic methods and by some chemical transformations.The chemotaxonomic situation is discussed briefly.Key Word Index - Aster umbellatus; A. exilis; Compositae; sesquiterpene lactones; new eudesmanolides; new selinene derivative; new tremetone derivative.
- Bohlmann, Ferdinand,Dutta, Lakshmi N.,Knauf, Werner,Robinson, Harold,King, Robert M.
-
-
Read Online
- Algal neurotoxin biosynthesis repurposes the terpene cyclase structural fold into an N-prenyltransferase
-
Prenylation is a common biological reaction in all domains of life wherein prenyl diphosphate donors transfer prenyl groups onto small molecules as well as large proteins. The enzymes that catalyze these reactions are structurally distinct from ubiquitous terpene cyclases that, instead, assemble terpenes via intramolecular rearrangements of a single substrate. Herein, we report the structure and molecular details of a new family of prenyltransferases from marine algae that repurposes the terpene cyclase structural fold for the N-prenylation of glutamic acid during the biosynthesis of the potent neurochemicals domoic acid and kainic acid. We solved the X-ray crystal structure of the prenyltransferase found in domoic acid biosynthesis, DabA, and show distinct active site binding modifications that remodel the canonical magnesium (Mg2+)-binding motif found in terpene cyclases. We then applied our structural knowledge of DabA and a homologous enzyme from the kainic acid biosynthetic pathway, KabA, to reengineer their isoprene donor specificities (geranyl diphosphate [GPP] versus dimethylallyl diphosphate [DMAPP]) with a single amino acid change. While diatom DabA and seaweed KabA enzymes share a common evolutionary lineage, they are distinct from all other terpene cyclases, suggesting a very distant ancestor to the larger terpene synthase family.
- Chekan, Jonathan R.,McKinnie, Shaun M. K.,Moore, Bradley S.,Noel, Joseph P.
-
p. 12799 - 12805
(2020/06/17)
-
- Structures and spasmolytic activities of derivatives from sesquiterpenes of Alpinia speciosa and Alpinia japonica
-
Sesquiterpenes isolated from Alpinia speciosa and Alpinia japonica, and their derivatives were found to inhibit histamine- or barium chloride- induced contraction of excised guinea pig ileum when tested by the Magnus method. Major spasmolytic principles contained in those extracts were the sesquiterpenes, β-eudesmol, nerolidol, humulene epoxide II and 4α- hydroxydihydroagarofuran. Relationships between the chemical structures of the sesquiterpenes and their derivatives, and their spasmolytic activities were discussed.
- Morita, Makoto,Nakanishi, Hiroshi,Morita, Hiroshi,Mihashi, Susumu,Itokawa, Hideji
-
p. 1603 - 1606
(2007/10/03)
-