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ENZYME entry: EC

Accepted Name
homospermidine synthase (spermidine-specific).
Reaction catalysed
putrescine + spermidine <=> propane-1,3-diamine + sym-homospermidine
  • A eukaryotic enzyme found in plants.
  • The reaction occurs in three steps, with some of the intermediates presumably remaining enzyme-bound: (1) NAD(+)-dependent dehydrogenation of spermidine to dehydrospermidine. (2) Attack by water forming 4-aminobutanal (and releasing propane- 1,3-diamine). (3) Condensation of 4-aminobutanal with purescine, which forms homospermidine and restores NAD(+).
  • This enzyme is more specific than EC, which is found in bacteria, as it cannot use putrescine as donor of the 4-aminobutyl group.
  • Forms part of the biosynthetic pathway of the poisonous pyrrolizidine alkaloids of the ragworts (Senecio).
PRIAM enzyme-specific profiles2.5.1.45
KEGG Ligand Database for Enzyme Nomenclature2.5.1.45
IUBMB Enzyme Nomenclature2.5.1.45
MEDLINEFind literature relating to
Rhea expert-curated reactions2.5.1.45
Q9SC13, HSS1_SENVE;  Q9M4B0, HSS1_SENVU;  P60038, HSS2_SENVE;  

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