Function
Polyamines are essential in all branches of life. Spermidine synthase (or putrescine aminopropyltransferase, polyamine aminopropyltransferase, PAPT) (SPS) catalyzes the biosynthesis of spermidine, a ubiquitous polyamine[1]. SPS catalyzes the transfer of aminopropyl group from decarboxylated S-adenosylmethionine (SAM) to the amine acceptor spermidine. N4-Bis(aminopropyl) spermidine synthase or branched-chain polyamine synthase is an aminopropyltransferase essential for synthesis of branched-chain polyamines which enables thermophiles to grow in high temperature environments[2].
Disease
SPS deficiency causes the intellectual disability Snyder-Robinson syndrome[3].
Structural highlights
[4]. Water molecules are shown as red spheres.
3D structures of spermidine synthase
Spermidine synthase 3D structures