Restriction Endonucleases and Exonucleases are enzymes that cut the nucleic acids, both DNA and RNA at specific sites. However, they both differ in their site of cutting.
Nucleases are enzymes that are known to cleave phosphodiester bonds in nucleic acids. They are an important tool in DNA repair and molecular cloning. On the basis of the locus of their activity, nucleases are divided into endonucleases and exonucleases.
Let us differentiate between the restriction endonucleases and exonucleases in the table below.
| Restriction endonucleases are enzymes that recognise DNA sequences, scan the sequence and cleave the fragment around or within that sequence. | Exonucleases are enzymes that cleave the polynucleotide sequence either from the 5’ end or the 3’ end, one at a time. |
| It is found only in prokaryotes. | It is found in both eukaryotes and prokaryotes. |
| The product obtained after cleavage is oligonucleotide chains. | The product obtained after exonuclease activity is monomers of nucleotides. |
| It cuts DNA at specific recognition sites. | It cuts DNA at random sites. |
| A restriction endonuclease activity either yields blunt ends or sticky ends. | Exonuclease activity always forms sticky ends. |
| Type I, II, III, IV and V | 5’ to 3’ exonuclease, 3’ to 5’ exonuclease and poly (A) specific 3’ to 5’ exonuclease. |
| It shows a lag period during their activity. | It does not show any lag period. |
| It plays a role in blocking cells from pathogens. | It does not have any role in blocking pathogens. |
| EcoRI, BamHI, Hind III | Snake venom, exonuclease 1, XRN 1. |
Explore BYJU’S Biology to learn more about restriction enzymes.
Also Read:
- How do restriction sites work?
- What is DNA restriction and modification?
- What Is Restriction Mapping?
- Does HindIII create sticky ends?
Frequently Asked Questions
What is the difference between DNA exonuclease and DNA endonuclease?
DNA exonucleases cleave the sequence from either end, whereas DNA endonucleases cleave the sequence within or adjacent to the sequence.
Is DNA polymerase an exonuclease?
DNA Polymerase I is an exonuclease that performs proofreading or editing activity of the DNA sequences.
What is UV endonuclease?
UV endonuclease or exonuclease are enzymes that are specific for DNA repair.
What is the function of exonuclease?
Exonucleases are involved in cellular metabolism and maintenance, important for genetic stability.
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