title: Biosynthetic intermediates and stereochemical aspects of aldehyde biosynthesis in the marine diatom Thalassiosira rotula.
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.
authors.affiliation: Istituto di Chimica Biomolecolare, CNR, Via Campi Flegrei 34, I-80078 Pozzuoli (Napoli), Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: d'Ippolito
authors.forename: Adele
authors.initials: A
authors.lastname: Cutignano
authors.forename: Sara
authors.initials: S
authors.lastname: Tucci
authors.forename: Giovanna
authors.initials: G
authors.lastname: Romano
authors.forename: Guido
authors.initials: G
authors.lastname: Cimino
authors.forename: Angelo
authors.initials: A
authors.lastname: Fontana
mesh_terms: D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism*; D000475:Alkenes / Q000737:chemistry; D017377:Diatoms / Q000737:chemistry* / Q000201:enzymology*; D015118:Eicosapentaenoic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D008084:Lipoxygenase / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D008968:Molecular Conformation; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
chemical_list: C508576:2E,4Z,7Z-decatrienal; D000447:Aldehydes; D000475:Alkenes; D005227:Fatty Acids; C474371:2,4-octadienal; D015118:Eicosapentaenoic Acid; D008084:Lipoxygenase