EC |
1.4.3.27 |
Accepted name: |
homospermidine oxidase |
Reaction: |
sym-homospermidine + 2 O2 + H2O = 1-formylpyrrolizidine + 2 H2O2 + 2 NH3 (overall reaction) (1a) sym-homospermidine + O2 = N-(4-aminobutylpyrrolinium) ion + H2O2 + NH3 (1b) N-(4-aminobutylpyrrolinium) ion + O2 + H2O = N-(4-oxobutylpyrrolinium) ion + NH3 + H2O2 (1c) N-(4-oxobutylpyrrolinium) ion = 1-formylpyrrolizidine (spontaneous)
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Glossary: |
(–)-trachelanthamidine = (1R,7aS)-hexahydro-1H-pyrrolizin-1-ylmethanol |
Other name(s): |
HSO |
Systematic name: |
homospermidine:oxygen oxidase (deaminating, cyclizing) |
Comments: |
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. |
References: |
1. |
Zakaria, M.M., Stegemann, T., Sievert, C., Kruse, L.H., Kaltenegger, E., Girreser, U., Cicek, S.S., Nimtz, M. and Ober, D. Insights into polyamine metabolism: homospermidine is double-oxidized in two discrete steps by a single copper-containing amine oxidase in pyrrolizidine alkaloid biosynthesis. Plant Cell 34 (2022) 2364–2382. [PMID: 35212762] |
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[EC 1.4.3.27 created 2022] |
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EC |
2.5.1.44 |
Accepted name: |
homospermidine synthase |
Reaction: |
(1) 2 putrescine = sym-homospermidine + NH3 (2) spermidine + putrescine = sym-homospermidine + propane-1,3-diamine |
Glossary: |
sym-homospermidine = N1-(4-aminobutyl)butane-1,4-diamine
putrescine = butane-1,4-diamine |
Other name(s): |
putrescine:putrescine 4-aminobutyltransferase (ammonia-forming) |
Systematic name: |
putrescine/spermidine:putrescine 4-aminobutyltransferase |
Comments: |
The reaction of this bacterial enzyme occurs in three steps, with some of the intermediates presumably remaining enzyme-bound: (a) NAD+-dependent dehydrogenation of either putrescine or spermidine, forming 4-iminobutan-1-amine or (E)-(4-aminobutylidene)(3-aminopropyl)amine, respectively, (b) attack by water forming 4-aminobutanal (and releasing ammonia or propane-1,3-diamine, respectively), and (c) condensation of 4-aminobutanal with putrescine, which forms homospermidine and restores NAD+. Differs from the eukaryotic enzyme EC 2.5.1.45, homospermidine synthase (spermidine-specific), which cannot use putrescine as donor of the aminobutyl group. |
References: |
1. |
Tait, G.H. The formation of homospermidine by an enzyme from Rhodopseudomonas viridis. Biochem. Soc. Trans. 7 (1979) 199–200. [PMID: 437275] |
2. |
Yamamoto, S., Nagata, S. and Kusaba, K. Purification and characterization of homospermidine synthase in Acinetobacter tartarogens ATCC 31105. J. Biochem. 114 (1993) 45–49. [PMID: 8407874] |
3. |
Ober, D., Tholl, D., Martin, W. and Hartmann, T. Homospermidine synthase of Rhodopseudomonas viridis: Substrate specificity and effects of the heterologously expressed enzyme on polyamine metabolism of Escherichia coli. J. Gen. Appl. Microbiol. 42 (1996) 411–419. |
4. |
Krossa, S., Faust, A., Ober, D. and Scheidig, A.J. Comprehensive Structural Characterization of the Bacterial Homospermidine Synthase-an Essential Enzyme of the Polyamine Metabolism. Sci. Rep. 6:19501 (2016). [PMID: 26776105] |
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[EC 2.5.1.44 created 1999, modified 2001] |
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EC |
2.5.1.45 |
Accepted name: |
homospermidine synthase (spermidine-specific) |
Reaction: |
spermidine + putrescine = sym-homospermidine + propane-1,3-diamine |
Glossary: |
sym-homospermidine = N1-(4-aminobutyl)butane-1,4-diamine
putrescine = butane-1,4-diamine
spermidine = N1-(3-aminopropyl)butane-1,4-diamine |
Systematic name: |
spermidine:putrescine 4-aminobutyltransferase (propane-1,3-diamine-forming) |
Comments: |
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). |
References: |
1. |
Böttcher, F., Ober, D. and Hartmann, T. Biosynthesis of pyrrolizidine alkaloids: putrescine and spermidine are essential substrates of enzymatic homospermidine formation. Can. J. Chem. 72 (1994) 80–85. |
2. |
Ober, D. and Hartmann, T. Homospermidine synthase, the first pathway-specific enzyme of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase. Proc. Natl. Acad. Sci. USA 96 (1999) 14777–14782. [PMID: 10611289] |
3. |
Ober, D., Harms, R. and Hartmann, T. Cloning and expression of homospermidine synthase from Senecio vulgaris: a revision. Phytochemistry 55 (2000) 311–316. [PMID: 11117877] |
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[EC 2.5.1.45 created 2001] |
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