Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Böttcher, C.; Roepenack-Lahaye, E. v.; Willscher, E.; Scheel, D.; Clemens, S.;Evaluation of Matrix Effects in Metabolite Profiling Based on Capillary Liquid Chromatography Electrospray Ionization Quadrupole Time-of-Flight Mass SpectrometryAnal. Chem.791507-1513(2007)DOI: 10.1021/ac061037q
The coupling of liquid chromatography to electrospray ionization quadrupole time-of-flight mass spectrometry can be a powerful tool for metabolomics, i.e., the comprehensive detection of low molecular weight compounds in biological systems. There have, however, been doubts about the feasibility and reliability of this approach, because LC−MSespecially with electrospray ionizationcan be subject to matrix effects. We evaluated matrix effects for our metabolomics platform in three ways: (i) postextraction addition of a set of reference compounds to different complex biological matrixes to determine absolute and relative matrix effects, (ii) postcolumn infusion of two reference compounds, and (iii) mixing of two complex matrixes. Our data demonstrate that there are indeed significant absolute matrix effects when comparing highly divergent samples. However, relative matrix effects are negligibleunless extremely divergent matrixes are comparedand do not compromise the relative quantification that is aimed for in nontargeted metabolomics studies. In conclusion, employing LC-coupled ESI-QTOF-MS for metabolomics studies is feasible yet rigorous validation is necessary.
Publikation
Günnewich, N.; Page, J. E.; Köllner, T. G.; Degenhardt, J.; Kutchan, T. M.;Functional Expression and Characterization of Trichome-Specific (-)-Limonene Synthase and (+)-α-Pinene Synthase from Cannabis sativaNat. Prod. Commun.(2007)DOI: 10.1177/1934578X0700200301
Two recombinant, stereospecific monoterpene synthases, a (-)-limonene synthase (CsTPS1) and a (+)-α-pinene synthase (CsTPS2), encoded by Cannabis sativa L. cv. ‘Skunk’ trichome mRNA, have been isolated and characterized. Recombinant CsTPS1 showed a Km value of 6.8 μM, a Vmax of 1.1 × 10−4 μmol/min and Vmax/Km of 0.016; the pH optimum was determined at pH 6.5, and a temperature optimum at 40°C. Recombinant CsTPS2 showed a Km value of 10.5 μM, a Vmax of 2.2 × 10−4 μmol/min and Vmax/Km of 0.021; the pH optimum was determined at pH 7.0, and a temperature optimum at 30°C. Phylogenetic analysis showed that both CsTPSs group within the angiosperms and belong to the Tpsb subgroup of monoterpene synthases. The enzymatic products (-)-limonene and (+)-α-pinene were detected as natural products in C. sativa trichomes.