Hydrolase that can act as a nucleoside triphosphatase and a dinucleoside polyphosphate pyrophosphatase. The best substrates are 8-oxo-dGTP and 8-oxo-GTP. Other substrates include Ap4A, dGTP and GTP. May be involved in protection from damage caused by radiation. 8-oxo-dGTP + H2O = 8-oxo-dGDP + H(+) + phosphate 8-oxo-GTP + H2O = 8-oxo-GDP + H(+) + phosphate H2O + P(1),P(4)-bis(5'-adenosyl) tetraphosphate = AMP + ATP + 2 H(+) Binds 3 Mg(2+) ions per subunit. kcat is 0.18 sec(-1) with 8-oxo-dGTP as substrate measured by the Pi sensor assay. kcat is 0.29 sec(-1) with 8-oxo-dGTP as substrate measured by the Fiske-SubbaRow assay. kcat is 0.13 sec(-1) with 8-oxo-GTP as substrate. Homodimer. Belongs to the Nudix hydrolase family.