ACC synthase EC 4.4.1.14; systematic name: S-adenosyl-L-methionine methylthioadenosine lyase; an enzyme present in plant tissues that catalyses the pyridoxal phosphate-dependent conversion of Sadenosylmethionine to 1-aminocyclopropane-1-carboxylic acid (ACC) and 5′-methylthioadenosine. It has been cloned from various fruits – zucchini (courgette), tomato, apple – and has 48–97% sequence identity in different plants. Tomato contains several genes for
accessory pigment any of the pigments, such as the yellow, red, or purple carotenoids and the red or blue phycobiliproteins in photosynthetic cells. The carotenoids are always present, whereas the phycobiliproteins occur only in algae belonging to the Rhodophyceae, the Cyanophyceae, and the Cryptophyceae. Strictly speaking, chlorophyll b is also an accessory pigment.
ACC oxidase an enzyme present in plant tissues that catalyses the Fe2+– and ascorbate-dependent oxidation of 1-aminocyclopropane-1- carboxylic acid (ACC) to ethylene, CO2, HCN, and H2O. It is a highly unstable monomer (35 kDa) that is inhibited by Co2+. Its activity increases under conditions of stress and at certain developmental stages (e.g. during fruit ripening).