24406-05-1Relevant articles and documents
A multiproduct terpene synthase from medicago truncatula generates cadalane sesquiterpenes via two different mechanisms
Garms, Stefan,Koellner, Tobias G.,Boland, Wilhelm
supporting information; experimental part, p. 5590 - 5600 (2010/11/20)
Terpene synthases are responsible for a large diversity of terpene carbon skeletons found in nature. The multiproduct sesquiterpene synthase MtTPS5 isolated from Medicago truncatula produces 27 products from farnesyl diphosphate (1, FDP). In this paper, we report the reaction steps involved in the formation of these products using incubation experiments with deuterium-containing substrates; we determined the absolute configuration of individual products to establish the stereochemical course of the reaction cascade and the initial conformation of the cycling substrate. Additional labeling experiments conducted with deuterium oxide showed that cadalane sesquiterpenes are mainly produced via the protonation of the neutral intermediate germacrene D (5). These findings provide an alternative route to the general accepted pathway via nerolidyl diphosphate (2, NDP) en route to sesquiterpenes with a cadalane skeleton. Mutational analysis of the enzyme demonstrated that a tyrosine residue is important for the protonation process.
Cloning and functional characterisation of a cis-muuroladiene synthase from black peppermint (Mentha × piperita) and direct evidence for a chemotype unable to synthesise farnesene
Prosser, Ian M.,Adams, Racheal J.,Beale, Michael H.,Hawkins, Nathan D.,Phillips, Andrew L.,Pickett, John A.,Field, Linda M.
, p. 1564 - 1571 (2008/02/11)
Using oligonucleotide primers designed to the known gene sequence of an (E)-β-farnesene (EβF) synthase, two cDNA sequences (MxpSS1 and MxpSS2) were cloned from a black peppermint (Mentha × piperita) plant. MxpSS1 encoded a protein with 96% overall amino acid sequence identity with the EβF synthase. Recombinant MxpSS1 produced in Escherichia coli, after removal of an N-terminal thioredoxin fusion, had a Km for FPP of 1.91 ± 0.1 μM and kcat of 0.18 s-1, and converted farnesyl diphosphate (FPP) into four products, the major two being cis-muurola-3,5-diene (45%) and cis-muurola-4(14),5-diene (43%). This is the first cis-muuroladiene synthase, to be characterised. MxpSS2 encoded a protein with only two amino acids differing from EβF synthase. Recombinant MxpSS2 protein showed no activity towards FPP. One of the two mutations, at position 531 (leucine in MxpSS2 and serine in EβF synthase) was shown, by structural modelling to occur in the J-K loop, an element of the structure of sesquiterpene synthases known to be important in the reaction mechanism. Reintroduction of the serine at position 531 into MxpSS2 by site-directed mutagenesis restored EβF synthase activity (Km for FPP 0.98 ± 0.12 μM, kcat 0.1 s-1), demonstrating the crucial role of this residue in the enzyme activity. Analysis, by GC-MS, of the sesquiterpene profile of the plant used for the cloning, revealed that EβF was not present, confirming that this particular mint chemotype had lost EβF synthase activity due to the observed mutations.
The role of germacrene D as a precursor in sesquiterpene biosynthesis: Investigations of acid catalyzed, photochemically and thermally induced rearrangements
Buelow, Nils,Koenig, Wilfried A
, p. 141 - 168 (2007/10/03)
Germacrene D is considered as a precursor of many sesquiterpene hydrocarbons. We have investigated the acid catalyzed as well as the photochemically and thermally induced rearrangement processes of germacrene D isolated from several Solidago species, which contain both enantiomers of germacrene D. Enantiomeric mixtures of sesquiterpenes of the cadinane, eudesmane (selinane), oppositane, axane, isodaucane, and bourbonane group as well as isogermacrene D were identified as main products and made available as reference compounds for structure investigations and stereochemical assignments of plant constituents. δ-Amorphene, one of the rearrangement products, was identified as a natural product for the first time. The absolute configuration of γ-amorphene was revised by correlation with the absolute configuration of germacrene D. The mechanisms of the rearrangement reactions are discussed. (C) 2000 Elsevier Science Ltd.
STABLE CARBOCATIONS FROM TERPENOIDS.IX. MOLECULAR REARRANGEMENTS OF α-MUROLENE AND α-COPAENE WITH THE FORMATION OF TRICYCLIC COMPOUNDS
Polovinka, M. P.,Mamatyuk, V. I.,Korchagina, D. V.,Sal'nikov, G. E.,Gatilov, Yu. V.,et al.
, p. 863 - 882 (2007/10/02)
Tricyclic compounds were obtained from α-murolene and α-copaene in superacidic media, and this agrees with the scheme for the biogenetic transformations of these substances.It was found that the temperature at which the stable cations are generated from α-murolene has an effect on the ratio of the paths leading to the formation of the bi- and tricyclic ions.The prediction of the most probable paths for the transformation of α-copaene agrees with the actually observed transformation of the stable ions generated from this substance.The preferred direction in the ske letal rearrangements of the investigated compounds depends on the nature of the acid medium.
Synthesis of (+/-)-α-Cadinene
Vig, O. P.,Bari, S. S.,Sharma, M. L.,Dua, D. M.
, p. 145 - 146 (2007/10/02)
Oxirane (III), prepared from 6-methyl-4-(1'-methylethyl)-3,4,4a,7,8,8a-hexahydro-1(2H)naphthalenone by reaction with dimethyloxosulphonium methylide, when cleaved with lithium diisopropylamide affords 1-hydroxymethyl-6-methyl-4-(1'-methylethyl)-3,4,4a,7,8,8a-hexahydronaphthalene (IV).Mesylate (V) from IV on treatment with LAH yields the (+/-)-α-cadinene(I).
