Endonuclease IV can act on a variety of oxidative damage in DNA

The enzyme is apurinic/apyrimidinic (AP) endonuclease that will hydrolyse intact AP sites in DNA. AP sites are cleaved at the first phosphodiester bond that is 5′ to the lesion leaving a hydroxyl group at the 3′ terminus and a deoxyribose 5′-phosphate at the 5′ terminus. The enzyme also has a 3′ -diesterease activity and can release phosphoglycoaldehyde, intact deoxyribose 5-phosphate and phosphate from the 3′ end of DNA.