The enzyme is involved in the biosynthesis of spermidine from agmatine in some archaea and bacteria. The enzyme from the Gram-negative bacterium Thermus thermophilus accepts agmatine, spermidine and norspermidine with similar catalytic efficiency. The enzymes from the archaea Pyrococcus furiosus and Thermococcus kodakarensis prefer agmatine, but can utilize cadaverine, putrescine and propane-1,3-diamine with much lower catalytic efficiency. cf. EC 2.5.1.16, spermidine synthase, and EC 2.5.1.23, sym-norspermidine synthase.
