ATP Citrate Lyase from Germinating Castor Bean Endosperm: Localization and some Properties.

ATP citrate lyase (EC 4.1.3.8) has been found in crude extracts from endosperm tissue of germinating castor bean and shows its maximum activity in 4- to 5-day-old seedlings. A strict requirement for coenzyme A and adenosine 5'-triphosphate was demonstrated. The pH optimum for the reaction is around 7.5. The unstable enzyme can be stabilized by freezing and addition of citrate and glycerol. (-)-Hydroxycitrate is a potent inhibitor. The molecular weight is about 400,000. The adenosine 5'-triphosphate citrate lyase is localized in the plastids, where it possibly plays a role in providing acetyl coenzyme A for lipid biosynthesis.