Biosynthetic intermediates and stereochemical aspects of aldehyde biosynthesis in the marine diatom Thalassiosira rotula |
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Authors: | d'Ippolito Giuliana Cutignano Adele Tucci Sara Romano Giovanna Cimino Guido Fontana Angelo |
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Affiliation: | Istituto di Chimica Biomolecolare, CNR, Via Campi Flegrei 34, I-80078 Pozzuoli (Napoli), Italy. |
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Abstract: | Intermediates of the aldehyde biosynthesis in Thalassiosira rotula are investigated. Use of labeled precursors and cell preparations proves production of 2E,4Z-octadienal from 6Z,9Z,12Z-hexadecatrienoic acid (C16:3 omega-4) through the lipoxygenase-dependent intermediate (9S)-9-hydroperoxyhexadeca-6,10,12-trienoic acid. On the contrary, synthesis of 2E,4Z,7Z-decatrienal involves mainly EPA (C20:5 omega-3) by a 11R-lipoxygenase, as suggested by identification of chiral 11R-HEPE (12% e.e.) in the diatom extracts. Consistently with the necessity to have a rapid transport and metabolization of the intermediate hydroperoxides, we show that lipoxygenase and lyase activities are both found in the same subcellular fraction of the microalga. |
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Keywords: | CET, carbethoxyethylidene CET-TPP, carbethoxyethylidene-triphenylphosphorane EPA, eicosapentaenoic acid GC-MS, gas chromatography-mass spectrometry HTrA, 6,9,12-hexadecatrienoic acid (C16:3 ω − 4) HTA, 6,9,12,15-hexadecatetraenoic acid (C16:4 ω − 1) 9S-HHTrE, (9S)-9-hydroxy-6Z,10E,12Z- hexadecatrienoic acid 9-HPHTrE, 9-hydroperoxy-6Z,10E,12Z-hexadecatrienoic acid 11-HEPE, 11-hydroxyeicosapentaenoic acid HPL, hydroperoxide lyase LOX, lipoxygenase NMR, nuclear magnetic resonance PUA, polyunsaturated short chain aldehydes |
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