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| Home > Publications database > Quantitative turnover analysis of chlorophylls, carotenoids and tocopherol in green leaves by LC-MS and FTICR-MS |
| Poster (Other) | FZJ-2017-02534 |
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2017
Abstract: Quantitative turnover analysis of chlorophylls, carotenoids and tocopherol in green leaves by LC-MS and FTICR-MSBjörn Thiele*, Andrea Neuwohner, Siegfried Jahnke, Ingar Janzik, Shizue MatsubaraIBG-2: Pflanzenwissenschaften, Forschungszentrum Jülich, D-52425 Jülich, GermanyAbstract: Chlorophylls and carotenoids are belonging to the photosynthetic pigments in chloroplasts of plants playing central roles in light absorption and photoprotection. Synthesis and degradation of photosynthetic pigments (chlorophylls and carotenoids) have been mostly studied in leaves during greening or senescence but not in mature leaves. The question how much biosynthesis and degradation of different photopigments occurs in photosynthesizing green leaves is still open. In order to gain insight into photopigment turnover of mature leaves we conducted long-term 13CO2 labelling with peppermint (Mentha x piperita) and analyzed the 13C/12C signature of chlorophylls (Chls), carotenoids and tocopherols (Toc) by LC-MS and FTICR-MS.Materials and Methods: Peppermint plants were cultivated in a 13CO2 containing atmosphere for 34 d [1]. Hereupon they were transferred to ambient CO2 where samples were collected from mature leaves over 7 days. Leave samples from day 0, 1, 2 and 7 were extracted and analyzed by LC-PDA-ESI(+)-MS using a C30 column. High resolved FTICR mass spectra were obtained from some exemplary samples in order to distinguish peaks of pigment isotopomers from those of co‐eluting matrix compounds and to assign mass peaks to distinct empirical formulae. The 13C degrees of labelling (DoL) of various photopigments over time were determined from the mass spectra. Additional MS/MS experiments were performed to gain insight into the position of 13C in the photopigment molecules. Results: The main photopigments in peppermint extracts were Chls a and b, -Toc and the xanthophylls lutein, zeaxanthin, antheraxanthin, neoxanthin (Neo) and violaxanthin and finally -carotene (-Car). While Chls and -Toc predominantly formed [M + H]+ adducts in the positive ESI mode, [M]+ and [M + H – H2O]+ adducts were additionally detected for carotenoids. After clearing up the mass spectra from matrix compound derived peaks DoLs were determined. Their time courses showed a high turnover for Chl a and -Car, a lower non-linear decline in DoL for xanthophylls but almost no change in the DoL for Neo. A distinct maximum peak in the mass spectra of -Toc from day 1 – 7 located between the extreme values for non-labelling and full labelling indicated a recycling of the phytol moiety during turnover of -Toc [2]. MS/MS experiments supported this hypothesis. Further results concerning turnover of Chls and xanthophylls will be also presented and discussed in the biological context.New Aspects: Regulation of photopigment metabolism in mature leavesReferences:[1] Gleichenhagen et al. (2013) Food Chem. 141: 2582‐2590.[2] Ischebeck et al. (2006) J. Biol. Chem. 281: 2470‐2477.Keywords: Turnover of photopigments, 13C labelling, LC-MS, FTICR-MS
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