Base excision repair (BER) glycosylase that initiates repair of A:oxoG to C:G by removing the inappropriately paired adenine base from the DNA backbone, generating an abasic site product (PubMed:25995449) (PubMed:14961129). 8-oxoguanine (oxoG) is a genotoxic DNA lesion resulting from oxidation of guanine; this residue is misread by replicative DNA polymerases, that insert adenine instead of cytosine opposite the oxidized damaged base. Shows a powerful dicrimination of A versus C, since it does not cleave cytosine in oxoG:C pairs (PubMed:25995449). May also be able to remove adenine from A:G mispairs, although this activity may not be physiologically relevant (PubMed:14961129). Hydrolyzes free adenine bases from 7,8-dihydro-8-oxoguanine:adenine mismatched double-stranded DNA, leaving an apurinic site. Binds 1 [4Fe-4S] cluster (PubMed:14961129, PubMed:25995449). The cluster has a structural role (PubMed:14961129). Belongs to the Nth/MutY family.