Crystal structure of the aminopropyltransferase, SpeE from hyperthermophilic crenarchaeon, Pyrobaculum calidifontis in complex with 5'-methylthioadenosine (MTA) and spermidine
Spermine and spermidine are polyamines. This family includes spermidine synthase that catalyses the fifth (last) step in the biosynthesis of spermidine from arginine, and spermine synthase.