Involved in the hydrolysis of the beta-gamma-phosphoanhydride linkage of triphosphate-containing substrates (inorganic or nucleoside-linked). Catalyzes the hydrolysis of inorganic triphosphate (PPPi). The enzyme has a strong preference for linear PPPi compared with cyclic PPPi (cyclic trimetaphosphate) and to the linear P4. The longer chains polyphosphate are not hydrolyzed. It has only a slight thiamine triphosphatase (ThTPase) activity. Nucleoside triphosphatase activity is negligible in the presence of magnesium, but a small activity is observed in the presence of manganese, in particular with GTP. H2O + triphosphate = diphosphate + phosphate Activated by magnesium and mangenese ions, and inhibited by calcium, zinc and copper ions. kcat is 288 sec(-1) for hydrolysis of PPPi (at pH 9.7 and 50 degrees Celsius). kcat is 76 sec(-1) for hydrolysis of PPPi (at pH 9.7 and 37 degrees Celsius). kcat is 19 sec(-1) for hydrolysis of PPPi (at pH 7.1 and 37 degrees Celsius). kcat is 0.36 sec(-1) for hydrolysis of ATP (at pH 8.1 and 50 degrees Celsius). Optimum pH is around 9.7. Optimum temperature is between 50 and 55 degrees Celsius. Homodimer.