Proton pumping inorganic pyrophosphatase of pea stem submitochondrial particles

Pea stem submitochondrial particles have an inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) which is able to couple PP(i) hydrolysis with the generation of an inside positive proton gradient. The activity is Mg2+-requiring, is stimulated by monovalent cations, inhibited by imidodiphosphate and, partially, by dicyclohexylcarbodiimide, diethylstilbestrol and oligomycin. This mitochondrial H+-PP(i)ase is distinguishable from the tonoplast H+-PP(i)ase and appears to be an additional coupling factor, which works in parallel with the well-known H+-ATPase.