2.5.1.45: homospermidine synthase (spermidine-specific)

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For detailed information about homospermidine synthase (spermidine-specific), go to the full flat file.

Reaction

Synonyms

homospermidine synthase, HSS, HSS1, synthase, homospermidine, synthase, homospermidine (Senecio vernalis root gene HSS1)

ECTree

     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 (only sub-subclass identified to date)

                2.5.1.45 homospermidine synthase (spermidine-specific)

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Results	in table
49	AA Sequence
2	CAS Registry Number
18	Cloned(Commentary)
9	Cofactor
5	Expression
23	General Information
1	General Stability
5	Inhibitors
5	Ki Value [mM]
5	KM Value [mM]
3	Localization
11	Molecular Weight [Da]
21	Natural Substrates/ Products (Substrates)
35	Organism
1	Pathway
1	pH Optimum
1	pH Range
7	Protein Variants
9	Purification (Commentary)
1	Reaction
1	Reaction Type
35	Reference
67	Source Tissue
7	Specific Activity [micromol/min/mg]
1	Storage Stability
36	Substrates and Products (Substrate)
10	Subunits
22	Synonyms
1	Systematic Name
1	Turnover Number [1/s]

Systematic Name

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Systematic Name on EC 2.5.1.45 - homospermidine synthase (spermidine-specific)

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SYSTEMATIC NAME

IUBMB Comments

spermidine:putrescine 4-aminobutyltransferase (propane-1,3-diamine-forming)

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).