1-aminocyclopropane-1-carboxylate

1-aminocyclopropane-1-carboxylate is the carboxyl-deprotonated form of 1-aminocyclopropane-1-carboxylic acid: a three-carbon ring bears an amino group and a carboxylate group on the same ring carbon. Its specified anionic form has formula ${\mathrm{C}}_4{\mathrm{H}}_6\mathrm{N}{\mathrm{O}}_2^{-}$. The familiar biochemical abbreviation ACC is also often used for the acid without specifying protonation.^[ref]

It is an intermediate between S-adenosylmethionine and Ethylene in plants. The 1979 apple experiments showed that labelled ACC became Ethylene in air and bypassed an inhibitor that blocked conversion from methionine. A supplied downstream intermediate restoring product formation helps locate the blocked reaction upstream.^[ref]