Spermidine synthase (SPDS)

Spermidine synthase is an enzyme (EC 2.5.1.16; commonly abbreviated as SPDS) that catalyzes the transfer of a propylamine group from decarboxylated S-adenosylmethionine (dc-SAM) to putrescine, forming spermidine. This step is a critical part of polyamine metabolism, which is essential for cell proliferation, differentiation, and growth in both prokaryotic and eukaryotic organisms[7][5]. Most spermidine synthases function as homodimers and possess a two-domain structure with a conserved active site for the aminopropyltransferase activity[5][7]. In plants, SPDS plays additional roles in stress responses and development[4][5]. Inhibition or dysregulation of spermidine synthase has been linked to cancer, infectious diseases, and potentially other disorders where polyamine homeostasis is disrupted. Several inhibitors (notably cyclohexylamine and decarboxylated S-adenosylhomocysteine) target the active site and are tools for mechanistic or therapeutic studies[2][5][7].

Other names

S-adenosylmethioninamine:putrescine 3-aminopropyltransferaseEC 2.5.1.16Putrescine aminopropyltransferaseSPDS

Competitive inhibition of the active site (e.g., by cyclohexylamine); Inhibition via substrate or cofactor analogs (e.g., decarboxylated S-adenosylhomocysteine)