In vitro repair of apurinic sites in DNA

Apurinic sites disappear from DNA during an incubation of the DNA with the Escherichia coli endonuclease specific for apurinic sites, DNA polymerase I (EC 2.7.7.7.), and T4 ligase (EC 6.5.1.1). Omission of any one of these three enzymes and, in particular, omission of the endonuclease specific for apurinic sites prevents this in vitro repair.