. . . . "spermidine + S-adenosyl-L-methioninamine → spermine + S-methyl-5'-thioadenosine + H+"^^ . "Spermidine aminopropyltransferase"^^ . "spermidine + S-adenosyl-L-methioninamine → spermine + S-methyl-5'-thioadenosine + H⁺"^^ . "2.5.1.22"^^ . . . . . . . . . . . "spermidine + S-adenosyl-L-methioninamine → spermine + S-methyl-5'-thioadenosine + H+"^^ .