The Enzyme Database

Your query returned 2 entries.    printer_iconPrintable version



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
For diagram of reaction, click here
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.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 76106-84-8
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]
[EC 2.5.1.44 created 1999, modified 2001]
 
 
EC 2.5.1.45     
Accepted name: homospermidine synthase (spermidine-specific)
Reaction: spermidine + putrescine = sym-homospermidine + propane-1,3-diamine
For diagram of reaction, click here
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).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
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. [DOI] [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]
[EC 2.5.1.45 created 2001]
 
 


Data © 2001–2021 IUBMB
Web site © 2005–2021 Andrew McDonald