Spermidine is a polyamine involved in cellular metabolism that can be used to stimulate the enzyme, T7 rna polymerase, a type of RNA polymerase. 
- Inhibits neuronal nitric oxide synthase (nNOS).
- Binds and precipitates DNA.
- may be used for purification of DNA binding proteins.
- Stimulates T4 polynucleotide kinase activity.