ATP- and phosphate-induced configurational changes of submitochondrial particles

Light scattering was employed to monitor configurational changes of submitochondrial particles. Such changes were induced by ATP but not by analogues of this nucleotide. Mg-2+ in an equimolar concentration to ATP enhanced the effect of the nucleotide. The ATP-induced changes were inhibited by oligomycin and uncouplers. Atractyloside was effective as an inhibitor only when loaded within the particles. The ATP-induced changes were decreased by phosphate. The effect of phosphate was partially inhibited by mersalyl. Sodium phosphate and ammonium phosphate were more effective than potassium phosphate. The observed changes in light scattering were due to (a) events involved in energization and de-energization of the membrane, and (b) events concerning transport over the particulate membrane. The changes were specific for adenine nucleotides and phosphate.