What is the mechanism of exonuclease?

Exonuclease is an enzyme that acts as a proofreader during DNA polymerization in the DNA replication process. It functions primarily to control genetic quality. Exonuclease works by scanning along the newly synthesized strand and removing any mismatched nucleotides from the free ends (either the 3' or 5' end) of a DNA or RNA strand. It does this by cleaving the phosphodiester bonds via hydrolysis. This results in the creation of overhangs called sticky ends at the cleavage sites.