Hydrolyzes deoxynucleoside triphosphates (dNTPs) to the corresponding nucleoside monophosphates. Has a strong preference for dCTP and its analogs including 5-iodo-dCTP and 5-methyl-dCTP for which it may even have a higher efficiency. May protect DNA or RNA against the incorporation of these genotoxic nucleotide analogs through their catabolism. dCTP + H2O = dCMP + diphosphate + H(+) Probably binds two or three Mg(2+) ions per subunit. Inhibited by divalent calcium or cadmium ions. Activity is higher with 5-iodo-dCTP, followed by 5-bromo-dCTP, dCTP, 5-methyl-dCTP and 5-chloro-dCTP. Hydrolyzes 2-chloro-dATP and 2-hydroxy-dATP with lower efficiency, and has even lower activity with dATP, dTTP and dUTP (in vitro). Does not hydrolyze ATP, UTP, ITP, GTP, dADP, dCDP or dGTP. Optimum pH is 9-9.5. Optimum temperature is 60 degrees Celsius. Homotetramer. Not detected in mitochondrion and nucleus. Ubiquitous. Highly expressed in heart, liver, skeletal muscle, cerebellum, brain, and salivary gland.