# Homospermidine synthase

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**Homospermidine synthase** () is an [enzyme](/source/Enzyme) with [systematic name](/source/List_of_enzymes) *putrescine:putrescine 4-aminobutyltransferase (ammonia-forming)*.[1][2][3][4][5][6] This enzyme [catalyses](/source/Catalysis) the following [chemical reaction](/source/Chemical_reaction)

- (1) 2 [putrescine](/source/Putrescine) \rightleftharpoons sym-homospermidine + NH3 + H+
- (2) putrescine + [spermidine](/source/Spermidine) \rightleftharpoons sym-homospermidine + propane-1,3-diamine

The reaction of this enzyme occurs in three steps.

## See also

[DHPS](/source/DHPS)

## References

1. Tait GH (February 1979). "The formation of homospermidine by an enzyme from Rhodopseudomonas viridis [proceedings]". *Biochemical Society Transactions*. **7** (1): 199–201. [doi:10.1042/bst0070199](https://doi.org/10.1042/bst0070199). [PMID 437275](https://pubmed.ncbi.nlm.nih.gov/437275)

1. Böttcher F, Ober D, Hartmann T (1994). "Biosynthesis of pyrrolizidine alkaloids: putrescine and spermidine are essential substrates of enzymatic homospermidine formation". *Can. J. Chem.*. **72** (1): 80–85. [Bibcode:1994CaJCh..72...80B](https://ui.adsabs.harvard.edu/abs/1994CaJCh..72...80B). [doi:10.1139/v94-013](https://doi.org/10.1139/v94-013)

1. Yamamoto S, Nagata S, Kusaba K (July 1993). "Purification and characterization of homospermidine synthase in Acinetobacter tartarogenes ATCC 31105". *Journal of Biochemistry*. **114** (1): 45–9. [doi:10.1093/oxfordjournals.jbchem.a124137](https://doi.org/10.1093/oxfordjournals.jbchem.a124137). [PMID 8407874](https://pubmed.ncbi.nlm.nih.gov/8407874)

1. Srivenugopal KS, Adiga PR (August 1980). "Enzymic synthesis of sym-homospermidine in Lathyrus sativus (grass pea) seedlings". *The Biochemical Journal*. **190** (2): 461–4. [doi:10.1042/bj1900461](https://doi.org/10.1042/bj1900461). [PMC 1162113](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1162113). [PMID 7470060](https://pubmed.ncbi.nlm.nih.gov/7470060)

1. Ober D, Tholl D, Martin W, Hartmann T (1996). "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** (5): 411–419. [doi:10.2323/jgam.42.411](https://doi.org/10.2323/jgam.42.411)

1. Ober D, Hartmann T (December 1999). "Homospermidine synthase, the first pathway-specific enzyme of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase". *Proceedings of the National Academy of Sciences of the United States of America*. **96** (26): 14777–82. [Bibcode:1999PNAS...9614777O](https://ui.adsabs.harvard.edu/abs/1999PNAS...9614777O). [doi:10.1073/pnas.96.26.14777](https://doi.org/10.1073/pnas.96.26.14777). [PMC 24724](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC24724). [PMID 10611289](https://pubmed.ncbi.nlm.nih.gov/10611289)

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Adapted from the Wikipedia article [Homospermidine synthase](https://en.wikipedia.org/wiki/Homospermidine_synthase) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Homospermidine_synthase?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.