Ligand-induced conformational changes of citrate synthase studied with the fluorescent probe 8-anilinonaphthalene 1-sulfonate.

Experiments are presented which show that oxaloacetate and analogs thereof with (R)-malate substructure, on interaction with citrate synthase linked to synthase 8-anilinonaphthalene 1-sulfonate (ANS), induce identical conformational changes of a characteristic magnitude. A conformational change of lower magnitude is also produced on binding of CoASH or ATP to citrate synthase.ANS and is completed on addition of oxaloacetate. The significance of these ligand-dependent conformational changes is discussed.