Latest documents http://publikationen.ub.uni-frankfurt.de/index/index/ Wed, 15 Aug 2012 13:48:07 +0200 Wed, 15 Aug 2012 13:48:07 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25594 The biosynthesis pathway to diadinoxanthin and fucoxanthin was elucidated in Phaeodactylum tricornutum by a combined approach involving metabolite analysis identification of gene function. For the initial steps leading to β-carotene, putative genes were selected from the genomic database and the function of several of them identified by genetic pathway complementation in Escherichia coli. They included genes encoding a phytoene synthase, a phytoene desaturase, a ζ-carotene desaturase, and a lycopene β-cyclase. Intermediates of the pathway beyond β-carotene, present in trace amounts, were separated by TLC and identified as violaxanthin and neoxanthin in the enriched fraction. Neoxanthin is a branching point for the synthesis of both diadinoxanthin and fucoxanthin and the mechanisms for their formation were proposed. A single isomerization of one of the allenic double bounds in neoxanthin yields diadinoxanhin. Two reactions, hydroxylation at C8 in combination with a keto-enol tautomerization and acetylation of the 3′-HO group results in the formation of fucoxanthin. Michael Dambek; Ulrike Eilers; Jürgen Breitenbach; Sabine Steiger; Claudia Büchel; Gerhard Sandmann article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25594 Wed, 15 Aug 2012 13:48:07 +0200