1-Aminocyclopropane-1-carboxylic acid (ACC) is a disubstituted cyclic alpha-amino acid in which a three-membered cyclopropane ring is fuzed to the C(alpha)-atom of the amino acid.
ACC plays an important role in the biosynthesis of the plant hormone ethylene. It is synthesized by the enzyme ACC synthase ( EC 4.4.1.14) from methionine and converted to ethylene by ACC oxidase (EC 1.14.17.4).
ACC is also a non-physiological partial agonist of the mammalian NMDA receptor.