Involved in the hydrolysis of the beta-gamma-phosphoanhydride linkage of triphosphate-containing substrates (inorganic or nucleoside-linked). Catalyzes vigorously the hydrolysis of inorganic triphosphate (PPPi), however it can also catalyze the hydrolysis of ATP to ADP and phosphate. It can use ribonucleotides such as GTP, CTP, or UTP and deoxynucleotides such as dATP, dGTP, dCTP, and dTTP. H2O + triphosphate = diphosphate + phosphate ATP + H2O = ADP + H(+) + phosphate kcat is 25 min(-1) for ATPase activity. Optimum pH is between 8 and 8.5 for ATPase activity and between 9 and 9.5 for PPPase activity. Hydrolysis of ATP declines sharply as the pH is increased to 9.5 or decreased to below 7.0. Homodimer.