1-aminocyclopropane-1-carboxylate synthase (ACS)

1-aminocyclopropane-1-carboxylate synthase (ACS) is a pyridoxal-5'-phosphate (PLP)-dependent enzyme that serves as the rate-limiting step in the biosynthesis of ethylene, a vital gaseous plant hormone [1, 2]. It catalyzes the conversion of S-adenosyl-L-methionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC) and 5'-methylthioadenosine [2, 4]. Ethylene is responsible for regulating various aspects of plant growth and development, including seed germination, fruit ripening, and responses to environmental stresses such as flooding or pathogen attack [1, 4]. Because of its central role in senescence and ripening, ACS is a major target for agricultural chemicals and genetic engineering aimed at extending the shelf life of fruits and flowers [2, 3]. Inhibitors such as aminoethoxyvinylglycine (AVG) and aminooxyacetic acid (AOA) act by competing with the PLP cofactor or the substrate, effectively reducing ethylene production [3, 4]. Although ACS is a critical target in plant biology and agriculture, it has no known direct role in human physiology or disease, as the ethylene biosynthetic pathway is absent in mammals [1, 2].

Other names

ACC synthaseS-adenosyl-L-methionine methylthioadenosine-lyase1-aminocyclopropane-1-carboxylic acid synthase

Competitive inhibition of the pyridoxal-5'-phosphate (PLP) cofactor binding site or the substrate binding site, preventing the conversion of S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylic acid [3, 4].