Entry |
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Name |
homospermidine synthase (spermidine-specific)
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Class |
Transferases;
Transferring alkyl or aryl groups, other than methyl groups;
Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date)
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Sysname |
spermidine:putrescine 4-aminobutyltransferase (propane-1,3-diamine-forming)
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Reaction(IUBMB) |
spermidine + putrescine = sym-homospermidine + propane-1,3-diamine [RN: R01919]
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Reaction(KEGG) |
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Substrate |
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Product |
sym-homospermidine [CPD: C06366];
propane-1,3-diamine [CPD: C00986]
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Comment |
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 4-iminobutan-1-amine, (b) attack by water forming 4-aminobutanal (and releasing propane-1,3-diamine), and (c) condensation of 4-aminobutanal with purescine, which forms 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).
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History |
EC 2.5.1.45 created 2001
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Orthology |
K21300 | homospermidine synthase (spermidine-specific) |
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Reference |
1 |
Authors |
Bottcher, F., Ober, D. and Hartmann, T. |
Title |
Biosynthesis of pyrrolizidine alkaloids: putrescine and spermidine are essential substrates of enzymatic homospermidine formation. |
Journal |
Can J Chem 72:80-85 (1994) |
Reference |
|
Authors |
Ober D, Hartmann T |
Title |
Homospermidine synthase, the first pathway-specific enzyme of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase. |
Journal |
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Sequence |
|
Reference |
|
Authors |
Ober D, Harms R, Hartmann T |
Title |
Cloning and expression of homospermidine synthase from Senecio vulgaris: a revision. |
Journal |
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Other DBs |
ExplorEnz - The Enzyme Database: | 2.5.1.45 |
ExPASy - ENZYME nomenclature database: | 2.5.1.45 |
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LinkDB |
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