| Parent Class: | EC-Numbers → 2 -- Transferases → 2.5 -- Transferring alkyl or aryl groups, other than methyl groups → 2.5.1 -- Transferring alkyl or aryl groups, other than methyl groups |
Systematic Name: spermidine:putrescine 4-aminobutyltransferase (propane-1,3-diamine-forming)
Unification Links: BRENDA:2.5.1.45, ENZYME:2.5.1.45, IUBMB-ExplorEnz:2.5.1.45
Reaction:
spermidine + putrescine → sym-homospermidine + propane-1,3-diamine
Enzymes and Genes:
deoxyhypusine synthase:
DHS1 (
Nicotiana tabacum
)
homospermidine synthase:
HSS1 (
Senecio vernalis
)
homospermidine synthase:
HSS (
Senecio vulgaris
)
Summary:
A eukaryotic enzyme found in plants. The reaction occurs in three steps, with some of the intermediates presumably remaining enzyme-bound: (a) NAD+-dependent dehydrogenation of
spermidine to
(E)-(4-aminobutylidene)(3-aminopropyl)amine, (b) attack by water forming
4-aminobutanal (and releasing propane-1,3-diamine), and (c) condensation of
4-aminobutanal with
putrescine, which forms
sym-homospermidine and restores NAD+. This enzyme is more specific than
EC 2.5.1.44, homospermidine synthase, 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).
Citations: [Bottcher94, Ober99, Bode00]
References
Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 46(D1):D633-D639 2018
Page generated by Pathway Tools version 28.5 (software by SRI International) on Sat Mar 29, 2025, BIOCYC14B.
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