Nuclease is an enzyme that breaks the nucleotide chain in DNA and RNA into smaller units.
The nuclease enzyme degrades the DNA molecule and disintegrates the bonds in phosphodiester that associate one nucleotide with another in the DNA strand.
The two different types of nucleases are: Exonucleases and Endonucleases
Types of nucleases:
Exonucleases:
Exonucleases remove nucleotides from a molecule of DNA.
Exonucleases include, for instance, snake venom, the 3' to 5' exonuclease domain of DNA polymerase III, spleen phosphodiesterase, the 5' to 3' exonuclease activity, and the 3' to 5' exonuclease domain of DNA polymerase I
Endonucleases:
Endonucleases break phosphodiester bonds within the molecule of DNA.
BamHI, EcoRI, EcoRV, HaeIII, and HindIII are a few instances of type II restriction endonucleases.
However, Type III also needs ATP to complete the DNA cleavage, which occurs roughly 25 base pairs from the recognition sequence.