DNA repair enzyme that is part of the base excision repair (BER) pathway; protects from oxidative damage by removing the major product of DNA oxidation, 8-oxoguanine (GO), from single- and double-stranded DNA substrates. 2'-deoxyribonucleotide-(2'-deoxyribose 5'-phosphate)-2'-deoxyribonucleotide-DNA = a 3'-end 2'-deoxyribonucleotide-(2,3-dehydro-2,3-deoxyribose 5'-phosphate)-DNA + a 5'-end 5'-monophospho-2'-deoxyribonucleoside-DNA + H(+) Highly thermostable. No decrease in activity was observed after heating 15 minutes at 80 degrees Celsius. Contains two alpha-helical subdomains, with the 8-oxoguanine binding site located in a cleft at their interface. Contains a helix-hairpin-helix (HhH) structural motif and a Gly/Pro-rich sequence followed by a conserved Asp (HhH-GPD motif). Belongs to the archaeal N-glycosylase/DNA lyase (AGOG) family.