Homospermidine synthase

Homospermidine synthase is an enzyme with systematic name putrescine:putrescine 4-aminobutyltransferase (ammonia-forming). This enzyme catalyses the following chemical reaction


 * (1) 2 putrescine $$\rightleftharpoons$$ sym-homospermidine + NH3 + H+
 * (2) putrescine + spermidine $$\rightleftharpoons$$ sym-homospermidine + propane-1,3-diamine

The reaction of this enzyme occurs in three steps.