39029-41-9Relevant academic research and scientific papers
Lessons from 1,3-Hydride Shifts in Sesquiterpene Cyclizations
Rinkel, Jan,Rabe, Patrick,Garbeva, Paolina,Dickschat, Jeroen S.
supporting information, p. 13593 - 13596 (2016/10/21)
Stereospecifically labelled precursors were subjected to conversion by seven bacterial sesquiterpene cyclases to investigate the stereochemistry of their initial 1,10-cyclisation-1,3-hydride shift cascades. Enzymes with products of known absolute configuration showed a coherent stereochemical course, except for (?)-α-amorphene synthase, for which the obtained results are better explained by an initial 1,6-cyclisation. The link between the absolute configuration of the product and the stereochemical course of the 1,3-hydride shifts enabled assignment of the absolute configurations of three enzyme products, which were confirmed independently through the absolute configuration of the common byproduct germacrene D-4-ol.
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.
5S,8S-GERMACRA-1E,6E-DIEN-5-OL FROM THE OLEORESIN OF Picea ajanensis AND ITS BIOMIMETIC CYCLIZATION
Raldugin, V. A.,Salenko, V. L.,Gamov, N. S.,Titova, T. F.,Khan, V. A.,Pentegova, V. A.
, p. 154 - 158 (2007/10/02)
From the oleoresin of the Yeddo spruce we have isolated a new sesquiterpene alcohol for which, on the basis of spectral and chemical chracteristics, the structure of 5S,8S-germacra-1E,6E-dien-5-ol (I) is suggested.The photocyclization of the alcohol isolated has given bourbonol, and its reaction with formic acid has yielded γ- and δ-cadinenes, the formates of T-muurolol and of T- and α-cadinols, and free T-muurolol and T- and α-cadinols
