Fpg (formamidopyrimidine [fapy]-DNA glycosylase), also known as 8-oxoguanine DNA glycosylase, acts both as an N-glycosylase and an AP-lyase

The N-glycosylase activity releases damaged purines from double-stranded DNA, generating an apurinic (AP) site. The AP-lyase activity cleaves both 3´ and 5´ to the AP site thereby removing the AP site and leaving a 1-base gap with a 5´ and 3´ phosphate. Some of the damaged bases recognized and removed by Fpg include 7, 8-dihydro-8-oxoguanine (8-oxoguanine), 8-oxoadenine, fapy-guanine, methy-fapy-guanine, fapy-adenine, aflatoxin B1-fapy-guanine, 5-hydroxy-cytosine and 5-hydroxy-uracil.