Spermine synthase (SMS)

Spermine synthase is a highly specific aminopropyltransferase enzyme (EC 2.5.1.22) that catalyzes the conversion of spermidine into spermine using decarboxylated S-adenosylmethionine as the aminopropyl donor. This enzyme is ubiquitously expressed in eukaryotes (including humans, animals, and plants) and is critical for polyamine biosynthesis, which is essential for cell growth, viability, DNA stabilization, and cellular stress responses. Structurally, spermine synthase is an obligate homodimer, with each monomer containing a C-terminal catalytic domain, a central domain forming a "lid" for the catalytic site, and an N-terminal domain crucial for dimerization. Mutations in the human SMS gene cause Snyder-Robinson syndrome, an X-linked recessive disorder characterized by intellectual disability, skeletal abnormalities, and movement disorders. Genetic deficiency in animal models also leads to sterility, deafness, reduced size, and early death. No approved drugs are known to therapeutically target spermine synthase, but its activity can be inhibited by reaction products such as 5'-methylthioadenosine[1][3][5].

Other names

spermidine aminopropyltransferasespermine synthetaseSMS

Inhibitors prevent conversion of spermidine to spermine; enzyme activity can be blocked by product inhibition (e.g., 5'-methylthioadenosine)[3].