Function
Pyrophosphatase that catalyzes the hydrolysis of nucleoside triphosphates to their monophosphate derivatives, with a high preference for the non-canonical purine nucleotides xanthosine triphosphate (XTP), deoxyinosine triphosphate (dITP) and ITP (PubMed:10404228, PubMed:11452035). Probably functions as a house-cleaning enzyme that removes non-canonical purine nucleotides from the nucleotide pool, thus preventing their incorporation into DNA/RNA and avoiding chromosomal lesions (PubMed:11452035). Shows very low activity on GTP or dGTP, both of which are hydrolyzed more than 100-fold less efficiently than XTP, and has nearly no activity toward the canonical nucleotides ATP, CTP, and TTP, and toward 6-N-hydroxylaminopurine deoxynucleoside triphosphate (dHAPTP) (PubMed:10404228, PubMed:11452035). Displays neither endonuclease nor 3'-exonuclease activities (PubMed:11452035).