Has nucleotide phosphatase activity toward ATP and GTP, but not toward CTP, TTP and ADP. ATP + H2O = ADP + H(+) + phosphate GTP + H2O = GDP + H(+) + phosphate kcat is 9.3 min(-1) and 0.57 min(-1) with ATP and GTP as substrate, respectively. Optimum pH is 6.0. Optimum temperature is 45 degrees Celsius.