Dictionary » E » Exonuclease



noun, plural:exonucleases

A nuclease that catalyzes the hydrolysis of phosphodiester bond, cleaving a single nucleotide from the end of a polynucleotide chain.


The enzyme may occur as individual enzyme or as part of a larger enzyme complex. For instance, DNA polymerase I has 3' to 5' exonuclease activity which is used in editing and proofreading DNA for errors.

Word origin: Greek éxō (outside) + nuclease.

Compare: endonuclease
See also: proofreading

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Re: 3' to 5' Exonuclease question

... forum. As I read about DNA Polymerase III in "molecular biology of the cell" the enzyme has both functions of polymerization 5'-3' and exonuclease 3'-5'. They locate in two active site of this enzyme. When a nucleotide is mismatched at polymerase site, the enzyme will stop and the mismatched ...

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by Duc
Mon Aug 08, 2011 4:20 am
Forum: Molecular Biology
Topic: 3' to 5' Exonuclease question
Replies: 2
Views: 3407

3' to 5' Exonuclease question

... from Berkley (one of those free online courses where they record the classes) says that "Polymerization is a race between the 3' to 5' exonuclease and polymerase" (probably polymerase III). What does that mean? How can it be a race since the DNA Polymerase is a holoenzyme/molecular ...

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by NathanielZhu
Thu Jul 07, 2011 2:03 am
Forum: Molecular Biology
Topic: 3' to 5' Exonuclease question
Replies: 2
Views: 3407

Single stranded DNA

probably by some nuclease. Maybe keep it with exonuclease for some time... Or you could try to digest normal DNA and then do some affinity chromatography specific for only one strand. But I don't know, whether you could get only one strand :(

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by JackBean
Tue Feb 22, 2011 5:54 pm
Forum: Genetics
Topic: Single stranded DNA
Replies: 5
Views: 2320

Mismatch DNA repair

... to perform apparently the same function (fill up a single strand gap resulting from excision). I know that Pol I has both 5' to 3' and 3' to 5' exonuclease activity whereas Pol III has only 3' to 5' exonuclease activity.

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by hullah
Wed Nov 10, 2010 5:31 am
Forum: Molecular Biology
Topic: Mismatch DNA repair
Replies: 4
Views: 3682


why can't you use other polymerase? The thing is that I need the exonuclease ability as well.

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by Skyrre
Mon May 10, 2010 6:43 am
Forum: Molecular Biology
Topic: Exonuclease (3'->5') protected PCR primers
Replies: 2
Views: 1580
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