Latest on enzymology of serotonin biosynthesis in walnut seeds.
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.
Schröder
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P
GSF National Research Center for Environment and Health, Neuherberg, Germany. pschroeder@gsf.de
Abele
C
C
Gohr
P
P
Stuhlfauth-Roisch
U
U
Grosse
W
W
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
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