Difference Wiki

Endonuclease vs. Exonuclease

The main difference between endonuclease and exonuclease is that endonuclease cuts nucleic acid strand at the middle, whereas exonuclease cuts nucleic acid strands from the ends.

Key Differences

The endonuclease creates a nick in between the nucleic acids, while exonuclease creates a nick at the end of the nucleic acid.
Endonuclease may form either sticky ends or blunt ends at the chains, but exonuclease always forms the sticky ends.
Samantha Walker
Sep 20, 2019
Endonuclease usually results in oligonucleotide chains after its hydrolytic activity; on the other hand, exonuclease results in single nucleosides or nucleotides after its hydrolytic reactions.
Various examples of endonuclease are S1 nuclease, DNases, and restriction enzymes such as Hind ׀׀׀, Bam H1, and Eco RI; on the contrary, some examples of exonuclease are spleen Phosphodiesterase, 3’ to 5’ exonuclease domain of the DNA polymerase ׀׀׀, snake venom, 5’ to 3’ exonuclease activity, and 3’ to 5’ exonuclease domain of DNA polymerase ׀.
Endonuclease plays an important role in blocking the entry of pathogens and other chemicals; on the other hand, exonuclease does not block the entry of pathogens.
Samantha Walker
Sep 20, 2019
Before the action of endonuclease, the restricted endonuclease undergoes a lag period, whereas before the motion of exonuclease it does not have a lag period.
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Endonuclease does not require a free 3’ to 5’ end for their act; conversely, exonuclease requires a free 3’ to 5’ end for their action.
Harlon Moss
Sep 20, 2019
The endonuclease is normally sequenced specifically; on the flip side, exonuclease is generally not- sequence-specific.
Endonuclease breaks phosphodiester bonds and forms restriction fragments, but they do not eliminate nucleotides one at a time, whereas exonuclease removes nucleotides one by one from the various ends of nucleic acids.
Janet White
Sep 20, 2019

Comparison Chart

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The endonuclease is a type of nucleases that nicks nucleic acids at the middle.
Exonuclease is the type of nuclease enzyme that nicks bonds or nucleic acids strands at the end.

Mechanism of Action

Cuts nucleic acids at the middle
Cuts nucleic acid at the ends

Lag Phase

Undergoes a lag period
Does not have a lag period
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Results

Results in oligonucleotide chains
Results in single nucleosides or nucleotides

Blunt/Sticky Ends

May form either sticky ends or blunt ends
Always form the sticky ends
Aimie Carlson
Sep 20, 2019

Role

Plays an important role in blocking the entry of pathogens
Does not play any significant role in blocking the entry of pathogens

Require Primers

Does not require a free 3’ to 5’ end for their action
Requires a free 3’ to 5’ end for their action

Sequence/Non-Sequence Specific

Sequence specific
Non-Sequence Specific
Harlon Moss
Sep 20, 2019

Examples

S1 nuclease, DNases, and restriction enzymes such as Hind ׀׀׀, Bam H1, and Eco RI
spleen Phosphodiesterase, snake venom 3’ to 5’ exonuclease domain of the DNA polymerase ׀׀׀, 5’ to 3’ exonuclease activity, and 3’ to 5’ exonuclease domain of DNA polymerase ׀
Aimie Carlson
Sep 20, 2019
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Endonuclease and Exonuclease Definitions

Endonuclease

Any of a group of enzymes that catalyze the hydrolysis of bonds between nucleotides in the interior of a DNA or RNA molecule.

Exonuclease

Any of a group of enzymes that catalyze the hydrolysis of single nucleotides from the end of a DNA or RNA chain.

Endonuclease

(enzyme) Any enzyme which catalyzes the cleavage of nucleic acids so as to produce variously sized fragments.

Exonuclease

Any of a group of enzymes which cleave single nucleotides from the end of a polynucleotide (DNA or RNA) chain.

Endonuclease

A nuclease that cleaves nucleic acids at interior bonds and so produces fragments of various sizes

Exonuclease

A nuclease that releases one nucleotide at a time (serially) beginning at one of a nucleic acid

Endonuclease vs. Exonuclease

The mechanism of endonuclease is that it cuts nucleic acids at the middle, while the exonuclease mechanism is that it cut nucleic acid at the ends. Before the activity of endonuclease, the restricted endonuclease undergoes a lag period, whereas before the activity of exonuclease it does not have a lag period. Endonuclease usually results in oligonucleotide chains after its hydrolytic activity; on the other hand, exonuclease results in single nucleosides or nucleotides after its hydrolytic reactions. Endonuclease may form either sticky ends or blunt ends, but exonuclease always forms the sticky ends. Endonuclease plays an important role in blocking the entry of pathogens; on the other hand, exonuclease does not play any significant role in blocking the entry of pathogens. Endonuclease does not require a free 3’ to 5’ end for their action; conversely, exonuclease requires a free 3’ to 5’ end for their action. The endonuclease is normally sequenced specifically; on the flip side, exonuclease is generally not- sequence-specific. Endonuclease breaks phosphodiester bonds and forms restriction fragments, but they do not eliminate nucleotides one by one, whereas exonuclease removes nucleotides one by one from the various ends of nucleic acids. Various examples of endonuclease are S1 nuclease, DNases, and restriction enzymes such as Hind ׀׀׀, Bam H1, and Eco RI; on the contrary, some examples of exonuclease are spleen Phosphodiesterase, 3’ to 5’ exonuclease domain of the DNA polymerase ׀׀׀, snake venom, 5’ to 3’ exonuclease activity, and 3’ to 5’ exonuclease domain of DNA polymerase ׀.

What is Endonuclease?

The endonuclease is a class of hydrolase and generally refers to an enzyme that cuts the polynucleotide chain at the middle by separating nucleotides other than two end ones. This result of endonuclease may result in two or more fragments of nucleic acids one at a time. The endonuclease is capable of acting on both RNA and DNA. Some endonucleases such as deoxyribonucleases (DNases) has non-specific cleavage. Though, many endonuclease target nucleotide sequences in a very specific manner and this is called restriction endonucleases because they are capable of recognizing the specific sequence of strands of nucleic acids. Therefore, these restricted endonucleases undergo lag periods before their action. The specific nucleotide sequence is called the restriction site.

Examples

Some examples of endonuclease are S1 nuclease, DNases, and restriction enzymes such as Hind ׀׀׀, Bam H1, and Eco RI.

What is Exonuclease?

Exonuclease is a type of hydrolases and usually refers to an enzyme that cuts the polynucleotide chain at the end of the chain by eliminating the nucleotides one at a time. Three types of exonuclease can be found in both eukaryotes and prokaryotes which are 3’ to 5’ exonuclease, 5’ to 3’ exonuclease, and poly (A)-specific 3’ to 5’ exonucleases. These all three types play a role in mRNA turnover. In E. coli, there are present 17 different types of exonucleases including DNA polymerase 1, 2, and 3. Exonuclease is very important in genetic recombination, genome stabilization, DNA repairing, prevention of the occurrence of mutations, etc.

Examples

Various examples of exonuclease are spleen Phosphodiesterase, snake venom, 3’ to 5’ exonuclease area of the DNA polymerase ׀׀׀, 5’ to 3’ exonuclease activity, and 3’ to 5’ exonuclease domain of DNA polymerase ׀.

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