1-aminocyclopropane-1-carboxylate synthase

Aminocyclopropane-1-carboxylic acid synthase (ACC synthase, ACS) (EC 4.4.1.14) is an enzyme that catalyzes the synthesis of 1-Aminocyclopropane-1-carboxylic acid (ACC), a precursor for ethylene, from S-Adenosyl methionine (AdoMet, SAM), an intermediate in the Yang cycle and activated methyl cycle and a useful molecule for methyl transfer. ACC synthase, like other PLP dependent enzymes, catalyzes the reaction through a quinonoid zwitterion intermediate and uses cofactor pyridoxal phosphate (PLP, the active form of vitamin B6) for stabilization. Aminocyclopropane-1-carboxylic acid synthase (ACC synthase, ACS) (EC 4.4.1.14) is an enzyme that catalyzes the synthesis of 1-Aminocyclopropane-1-carboxylic acid (ACC), a precursor for ethylene, from S-Adenosyl methionine (AdoMet, SAM), an intermediate in the Yang cycle and activated methyl cycle and a useful molecule for methyl transfer. ACC synthase, like other PLP dependent enzymes, catalyzes the reaction through a quinonoid zwitterion intermediate and uses cofactor pyridoxal phosphate (PLP, the active form of vitamin B6) for stabilization. In enzymology, a 1-aminocyclopropane-1-carboxylate synthase is an enzyme that catalyzes the chemical reaction Hence, this enzyme has one substrate, S-adenosyl-L-methionine, and two products, 1-aminocyclopropane-1-carboxylate and methylthioadenosine. This enzyme belongs to the family of lyases, specifically carbon-sulfur lyases. The systematic name of this enzyme class is S-adenosyl-L-methionine methylthioadenosine-lyase(1-aminocyclopropane-1-carboxylate-forming). Other names in common use include 1-aminocyclopropanecarboxylate synthase, 1-aminocyclopropane-1-carboxylic acid synthase, 1-aminocyclopropane-1-carboxylate synthetase, aminocyclopropanecarboxylic acid synthase, aminocyclopropanecarboxylate synthase, ACC synthase, and S-adenosyl-L-methionine methylthioadenosine-lyase. This enzyme participates in propanoate metabolism. It employs one cofactor, pyridoxal phosphate. The reaction catalyzed by 1-aminocyclopropane-1-carboxylic acid synthase (ACS) is the committed and rate-limiting step in the biosynthesis of ethylene , a gaseous plant hormone that is responsible for the initiation of fruit ripening, shoot and root growth and differentiation, leaf and fruit abscission, flower opening, and flower and leaf senescence. (source) It is a pyridoxal phosphate (PLP) dependent gamma-elimination (?). In the gamma elimination, PLP acts as a sink twice (absorbing electrons from two deprotonations).