An extract from ripe pear fruits was used to demonstrate that 1- aminocyclopropane-1-carboxylate (ACC) oxidase, the enzyme responsible for plant ethylene synthesis, is sensitive to inhibition by a range of 2- oxoacids, competitively with respect to the co-substrate ascorbic acid, and non-competitively with respect to ACC, and to the co-factors, iron (II) and carbon dioxide. The significance of the findings is discussed in terms of the reaction mechanism of ACC oxidase, an enzyme which is related by primary sequence to the family of iron (II)-dependent dioxygenases, most of which use 2-oxoglutarate as a co-substrate.
