Chapter

Tryptophan, Serotonin, and Melatonin

Volume 467 of the series Advances in Experimental Medicine and Biology pp 637-644

Latest on Enzymology of Serotonin Biosynthesis in Walnut Seeds

  • Peter SchröderAffiliated withGSF National Research Center for Environment and Health
  • , Claudia AbeleAffiliated withBotanical Institute, University of Cologne
  • , Petra GohrAffiliated withBotanical Institute, University of Cologne
  • , Uta Stuhlfauth-RoischAffiliated withBotanical Institute, University of Cologne
  • , Wolfgang GrosseAffiliated withBotanical Institute, University of Cologne

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Abstract

Serotonin (5-HT) accumulation in walnut cotyledons is seen as a detoxification mechanism protecting the sensitive plant tissues of seeds from highly toxic ammonia concentrations following seed desiccation. Different metabolic pathways and cell compartments are involved in biosynthesis and storage of 5-HT. Ammonia fixation and incorporation into the indole moiety of tryptophan is followed by 5-HT biosynthesis via tryptamine in a two-step pathway with the adaptive tryptophan decarboxylase and the constitutive tryptamine 5-hydroxylase. Evidence is provided that tryptamine 5-hydroxylase is a member of the cytochrome P450 family which is involved in lipid hydroxylation processes in the very early period of seed development.