title: Latest on enzymology of serotonin biosynthesis in walnut seeds.
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.
authors.affiliation: GSF National Research Center for Environment and Health, Neuherberg, Germany. pschroeder@gsf.de
authors.forename: P
authors.initials: P
authors.lastname: Schröder
authors.forename: C
authors.initials: C
authors.lastname: Abele
authors.forename: P
authors.initials: P
authors.lastname: Gohr
authors.forename: U
authors.initials: U
authors.lastname: Stuhlfauth-Roisch
authors.forename: W
authors.initials: W
authors.lastname: Grosse
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism*; D018548:Cotyledon / Q000201:enzymology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008027:Light; D008861:Microsomes / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009754:Nuts / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology; D012701:Serotonin / Q000096:biosynthesis*; D013379:Substrate Specificity; D014363:Tryptamines / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
chemical_list: D014363:Tryptamines; D012701:Serotonin; C030820:tryptamine; D000641:Ammonia; D014364:Tryptophan; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C407366:tryptamine 5-hydroxylase; D001142:Aromatic-L-Amino-Acid Decarboxylases