What is the difference between Endonuclease and Exonuclease?

When you say endonuclease, you are referring to a group of enzymes that can be found in a polynucleotide chain. Take note that they will cleave the phosphodiester bond. Exonuclease, on the other hand, are those that will cleave the DNA sequences but this time, in a polynucleotide chain.

They will cleave the chain in the middle portion. Take note that the endonuclease will be able to cleave double-stranded or single-stranded DNA. They can also cleave RNA. Exonuclease is also important for proofreading DNA or RNA especially when there are some possible errors.

Endonuclease and exonuclease share the fact that they are both nuclease enzymes. Their function is to serve as a catalyst for the hydrolysis process that happens with single nucleotides. This happens in the DNA chain.

The results of the activity that both of these enzymes occur is one of the differences between them. Exonuclease ends in nucleosides. Endonuclease ends in olginonucleotides. Another difference is the length of time that they release units.

Exonuclease releases units immediately. An example of this is with snake venom. endonuclease differs because it releases the units after a lag. An example of this is with deoxyribonuclease.

Endonucleases are a group of enzymes that catalyze the cleavage of the phosphodiester bond that is found within the polynucleotide chain. On the other hand, exonucleases are a group of enzymes that break or cleave nucleotides or DNA sequences present in a polynucleotide chain, usually at position 5 or 3 of the polynucleotide chain.

Unlike endonucleases that cleave nucleotides from the middle of the of a polynucleotide chain, exonucleases cleave nucleotides from the ends of a polynucleotide. Both types of enzymes do not have a lag period before they start their work. However, some endonucleases suffer from this; they are called restriction endonucleases.

The reason is that they need enough time to recognize their specific sites. After the cleavage of polynucleotides by endonucleases, the compounds formed are known as oligonucleotides. On the other hand, after the cleavage of polynucleotides by exonucleases, the compounds formed are known as nucleosides or nucleotides.

The term exonuclease refers to any of a group of enzymes that cleave or attach to the nucleotides from the end of a polynucleotide chain, DNA or RNA. Since exonucleases cleave the nucleotides from the back, they hydrolyze the phosphodiester bond at the 3 and 5 arms of the polynucleotides. On the other hand, the term endonuclease refers to a group of enzymes that cleave to the nucleotides from the interior of the polynucleotides. They work by hydrolyzing the phosphodiester bonds that are within a polynucleotide chain.

Unlike exonucleases that hydrolyze at the 3 or 5 hydroxyl group of the nucleotides present in the polynucleotide chain, endonuclease enzymes do not need to cleave to the 3 or 5 hydroxyl group of the nucleotides present in the polynucleotide chain before they can cause the hydrolysis of a RNA of DNA chain. Unlike endonucleases that produce oligonucleotides, exonucleases lead to nucleosides.

Both Endonuclease and the exonuclease are actually nuclease enzymes which function is to catalyze the hydrolysis of single nucleotides, which is present in a chain of DNA. Nucleases do play vital roles in the analysis of the sequence of nucleotides in DNA and RNA.

Exonuclease does cause the hydrolysis of a nucleotide at the ends in which there is the presence of a free 3’ or 5’ hydroxyl group in the polynucleotide chain, but the exonuclease does not actually require a free 3’ or 5’ hydroxyl group to effect the hydrolysis of the polynucleotide chain. The activity of exonuclease usually results in nucleosides, while that of endonuclease results in oligonucleotides.

The activity of exonuclease results in the smaller units of the polynucleotide chain immediately, but endonuclease activity goes through a lag phase before they release oligonucleotide groups. Snake venom and the spleen phosphodiesterase are examples of exonucleases, but deoxyribonuclease is examples of endonucleases.