Structure and mechanism of spermidine synthases

Biochemistry. 2007 Jul 17;46(28):8331-9. doi: 10.1021/bi602498k. Epub 2007 Jun 22.


Aminopropyltransferases transfer aminopropyl groups from decarboxylated S-adenosylmethionine to amine acceptors, forming polyamines. Structural and biochemical studies have been carried out with the human spermidine synthase, which is highly specific for putrescine as the amine acceptor, and the Thermotoga maritima spermidine synthase, which prefers putrescine but is more tolerant of other substrates. Comparison of the structures of the human spermidine synthase with both substrates and products with the known structure of T. maritima spermidine synthase complexed to a multisubstrate analogue inhibitor and analysis of the properties of site-directed mutants provide a general mechanistic hypothesis for the aminopropyl transfer reaction. The studies also provide a structural basis for the specificity of the spermidine synthase subclass of the aminopropyltransferase family.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Crystallography, X-Ray
  • Humans
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Putrescine / chemistry
  • Spermidine Synthase / chemistry*
  • Spermidine Synthase / genetics
  • Substrate Specificity
  • Thermotoga maritima / enzymology


  • Spermidine Synthase
  • Putrescine

Associated data

  • PDB/1IY9
  • PDB/1MJF
  • PDB/1UIR
  • PDB/1XJ5
  • PDB/2HTE