Which exonuclease acts on both ends of single-stranded DNA?

Exonuclease VII is characterized by its capability to act on both ends of single-stranded DNA, making it unique among the exonucleases listed. This enzyme specializes in the degradation of single-stranded DNA and can remove nucleotides from the 5' and 3' ends, thereby allowing it to process various forms of single-stranded DNA efficiently.

This ability to act on both ends is particularly useful in molecular biology applications, such as preparing DNA for cloning or sequencing. By trimming back single-stranded regions from both ends, Exonuclease VII can facilitate the generation of blunt or cohesive ends required for ligation or other enzymatic reactions.

In contrast, the other exonucleases mentioned have more specific activities; for instance, Exonuclease I primarily degrades single-stranded DNA from the 3' end, whereas Exonuclease III works on double-stranded DNA by removing nucleotides from the 3' ends. Mung Bean nuclease cuts single-stranded DNA but typically does not act on both ends in the same way as Exonuclease VII. Thus, Exonuclease VII is the best fit for the question regarding an enzyme that acts on both ends of single-stranded DNA