Catalyzes the irreversible hydrolysis of pyrophosphate (PPi) to phosphate. The MgPPi(2-) complex binds to the enzyme only after a free Mg(2+) ion has bound. No activity with glycerol-3-phosphate, glucose-6-phosphate, p-nitrophenylphosphate, ADP, NADP(+), NAD(+),NADH, NADPH or phosphoribosyl pyrophosphate as substrates. diphosphate + H2O = H(+) + 2 phosphate Inhibited by Zn(2+), Ca(2+), Ba(2+), Fe(2+), Co(2+), Cu(2+), Eu(2+), Eu(3+) and Mn(2+). kcat is 9.20 sec(-1) for pyrophosphate. Monomer. Ubiquitous, excepted in pollen. Very low expression in cork, xylem and hypocotyls. Expressed throughout plant development, with a lower expression in young plantes and a maximum during flowering. Belongs to the PPase family.