Structure, catalytic activity and evolutionary relationships of 1-aminocyclopropane-1-carboxylate synthase, the key enzyme of ethylene synthesis in higher plants.

Both ethylene and the enzymes of ethylene synthesis are subjects of intensive scientific investigation. The present review discusses structure, catalytic activity and evolutionary relationships of 1-aminocyclopropane-1-carboxylate synthase, identified for the first time in ripening tomato in 1979. This enzyme is responsible for the conversion of S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylic acid, which is the key step of ethylene synthesis in higher plants. The role of this enzyme (especially in the fruit ripening) was demonstrated in 1991 in transgenic tomato plants, expressing 1-aminocyclopropane-1-carboxylate synthase antisense RNA. On the basis of mutagenesis and crystallization of the enzyme, new data were provided on the three-dimensional structure and amino-acid residues which are critical for catalysis. The control of ethylene production is of great interest for plant biotechnology because it can delay senescence and overmaturation. These processes are responsible for large loss of vegetables and fruit on storage. Detailed structural and biochemical data are necessary to help design 1-aminocyclopropane-1-carboxylate synthase inhibitors, whose application is expected to have immense agricultural effects.