KEGG   ENZYME: 1.4.3.27
Entry
EC 1.4.3.27                 Enzyme                                 
Name
homospermidine oxidase;
HSO
Class
Oxidoreductases;
Acting on the CH-NH2 group of donors;
With oxygen as acceptor
Sysname
homospermidine:oxygen oxidase (deaminating, cyclizing)
Reaction(IUBMB)
sym-homospermidine + 2 O2 + H2O = 1-formylpyrrolizidine + 2 H2O2 + 2 NH3 (overall reaction) [RN:R13141];
(1a) sym-homospermidine + O2 = N-(4-aminobutylpyrrolinium) ion + H2O2 + NH3 [RN:R13138];
(1b) N-(4-aminobutylpyrrolinium) ion + O2 + H2O = N-(4-oxobutylpyrrolinium) ion + NH3 + H2O2 [RN:R13139];
(1c) N-(4-oxobutylpyrrolinium) ion = 1-formylpyrrolizidine (spontaneous) [RN:R13140]
Reaction(KEGG)
Substrate
sym-homospermidine [CPD:C06366];
O2 [CPD:C00007];
H2O [CPD:C00001];
N-(4-aminobutylpyrrolinium) ion [CPD:C22646];
N-(4-oxobutylpyrrolinium) ion [CPD:C22647]
Product
1-formylpyrrolizidine [CPD:C22648];
H2O2 [CPD:C00027];
NH3 [CPD:C00014];
N-(4-aminobutylpyrrolinium) ion [CPD:C22646];
N-(4-oxobutylpyrrolinium) ion [CPD:C22647]
Comment
The copper-containing enzyme has been isolated from the plant Heliotropium indicum. It is involved in the biosynthesis of the pyrrolizidine alkaloid (-)-trachelanthamidine which acts as a secondary metabolite for the defense against herbivores. The oxidation of sym-homospermidine proceeds in three steps and results in a cyclization.
History
EC 1.4.3.27 created 2022
Orthology
K26346  homospermidine oxidase
Genes
SMIL130991493 130991497
RVL131310176
AEW130757234
Reference
1  [PMID:35212762]
  Authors
Zakaria MM, Stegemann T, Sievert C, Kruse LH, Kaltenegger E, Girreser U, Cicek SS, Nimtz M, Ober D.
  Title
Insights into polyamine metabolism: homospermidine is double-oxidized in two discrete steps by a single copper-containing amine oxidase in pyrrolizidine alkaloid biosynthesis.
  Journal
Plant Cell 34:2364-2382 (2022)
DOI:10.1093/plcell/koac068
  Sequence
Other DBs
ExplorEnz - The Enzyme Database: 1.4.3.27
IUBMB Enzyme Nomenclature: 1.4.3.27
ExPASy - ENZYME nomenclature database: 1.4.3.27
BRENDA, the Enzyme Database: 1.4.3.27

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