What type of enzymes are exonucleases?

Exonucleases are specific enzymes that play a key role in the degradation of nucleic acids, primarily by removing nucleotide units from the ends of a DNA or RNA molecule. They function by cleaving nucleotides from the terminal ends rather than cutting at internal sites. This process is crucial for various cellular activities, including DNA repair, replication, and the regulation of nucleic acid turnover.

The choice of degradation as the defining function of exonucleases is significant, as it distinguishes them from other enzyme types in molecular biology. For example, polymerases are responsible for synthesizing nucleic acids, while ligases are involved in joining DNA segments together. Helicases, on the other hand, unwind DNA strands to facilitate replication and transcription, but they do not degrade nucleic acids.

Understanding exonucleases is important for studying genetic material's stability and integrity, as well as their applications in molecular diagnostics and research.