Enzyme
Homospermidine synthase (EC 2.5.1.44 ) is an enzyme with systematic name putrescine:putrescine 4-aminobutyltransferase (ammonia-forming) .[ 1] [ 2] [ 3] [ 4] [ 5] [ 6] This enzyme catalyses the following chemical reaction
(1) 2 putrescine
⇌
{\displaystyle \rightleftharpoons }
sym-homospermidine + NH3 + H+
(2) putrescine + spermidine
⇌
{\displaystyle \rightleftharpoons }
sym-homospermidine + propane-1,3-diamine
The reaction of this enzyme occurs in three steps.
^ 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 . PMID 437275 .
^ 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 : 80–85. doi :10.1139/v94-013 .
^ 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 . PMID 8407874 .
^ 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 . PMC 1162113 . PMID 7470060 .
^ 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 .
^ 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 . doi :10.1073/pnas.96.26.14777 . PMC 24724 . PMID 10611289 .