DNA-(apurinic or apyrimidinic site) endonuclease activity carbon-oxygen lyase activity class I DNA-(apurinic or apyrimidinic site) endonuclease activity https://github.com/geneontology/go-ontology/issues/22262 https://github.com/geneontology/go-ontology/issues/27071 https://github.com/geneontology/go-ontology/issues/30193 Catalysis of the cleavage of an AP site 3' of the baseless site by a beta-lyase mechanism, leaving an unsaturated aldehyde, termed a 3'-(4-hydroxy-5-phospho-2-pentenal) residue, and a 5'-phosphate. GO:0140078 AP site-DNA 5'-phosphomonoester-lyase activity class I DNA-(apurinic or apyrimidinic site) lyase activity Wikipedia:AP_endonuclease DNA-(apurinic or apyrimidinic site) 5'-phosphomonoester-lyase activity AP endonuclease class I activity EC:4.2.99.18 pg class I AP endonuclease activity RHEA:66592 DNA-(apurinic or apyrimidinic site) lyase activity 2017-07-24T11:33:34Z MetaCyc:4.2.99.18-RXN molecular_function AP lyase activity