In enzymology, a nicotianamine synthase (EC 2.5.1.43) is an enzyme that catalyzes the chemical reaction

3 S-adenosyl-L-methionine ${\displaystyle \rightleftharpoons }$ 3 S-methyl-5'-thioadenosine + nicotianamine

Hence, this enzyme has one substrate, S-adenosyl-L-methionine, and two products, S-methyl-5'-thioadenosine and nicotianamine.

This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is S-adenosyl-L-methionine:S-adenosyl-L-methionine:S-adenosyl-Lmethioni ne 3-amino-3-carboxypropyltransferase.