Nucleases that cleave near the ends of DNA molecules are called exonucleases while enzymes that cleave within a DNA strand and do not require a free DNA end for cleavage are called endonucleases. Some enzymes have both activities.

Does nuclease break down DNA?

nuclease, any enzyme that cleaves nucleic acids. Nucleases, which belong to the class of enzymes called hydrolases, are usually specific in action, ribonucleases acting only upon ribonucleic acids (RNA) and deoxyribonucleases acting only upon deoxyribonucleic acids (DNA).

What does a nuclease cut?

Nucleases that can cut DNA at specific sites have been discovered in bacteria and the enzymes are commercially available. These enzymes are called restriction endonucleases or simply, restriction enzymes. Endonucleases cut DNA in the interior of the molecule while exonucleases cut DNA at the ends of the molecule.