EC 18.104.22.168 - Homospermidine synthase (spermidine-specific)
IntEnz Enzyme Nomenclature
11236 [IUBMB]putrescineputrescineName origin: UniProt - CHECKED (C)Formula: C4H14N2
Charge: 2ChEBI compound status: CHECKED (C)spermidinespermidineName origin: UniProt - CHECKED (C)Formula: C7H22N3
Charge: 3ChEBI compound status: CHECKED (C)<?>sym-homospermidinesym-homospermidineName origin: UniProt - CHECKED (C)Formula: C8H24N3
Charge: 3ChEBI compound status: CHECKED (C)
The reaction of this enzyme occurs in three steps: (i) NAD+-dependent dehydrogenation of spermidine, (ii) transfer of the 4-aminobutylidene group from dehydrospermidine to putrescine, (iii) reduction of the imine intermediate to form homospermidine. Hence the overall reaction is transfer of a 4-aminobutyl group. This enzyme is more specific than EC 22.214.171.124, 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).
Links to other databases
Biosynthesis of pyrrolizidine alkaloids: putrescine and spermidine are essential substrates of enzymatic homospermidine formation.Can. J. Chem. 72: 80-85 (1994).
Homospermidine synthase, the first pathway-specific enzyme of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase.Proc. Natl. Acad. Sci. USA 96: 14777-14782 (1999). [PMID: 10611289]
Cloning and expression of homospermidine synthase from Senecio vulgaris: a revision.Phytochemistry 55: 311-316 (2000).
[EC 126.96.36.199 created 2001]