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Dictionary » E » Exonuclease

Exonuclease

Definition

noun, plural:exonucleases

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


Supplement

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: Proving Existence of Introns!

... red is radioactively labeled chromosomal DNA containing the gene for Beta globin. You first hybridize them. then treat with either S1 nuclease or exonuclease VII. S1 nuclease is an enzyme that degrades all single stranded DNA, exonuclease VII only degrades single stranded DNA that has a free (either ...

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by MrMistery
Thu Jan 22, 2009 2:48 am
 
Forum: Genetics
Topic: Proving Existence of Introns!
Replies: 4
Views: 479

DNA Mismatch repair

During DNA mismatch repair when the exonuclease makes an insicion and begins repair on the daughter strand HOW does it know when to stop excising nucleotides after it excises the mismatch.

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by canan5000
Mon Feb 25, 2008 11:38 pm
 
Forum: Molecular Biology
Topic: DNA Mismatch repair
Replies: 1
Views: 349

Re: Identify the nucleic acid!

... much, Cat. I’d still bet on rRNA, though on further reflection, the question may not be answerable with the information given. I see that lambda exonuclease cannot initiate digestion from a nick or a gap (although it does have very weak activity against ssDNA or so says the descriptive blurb ...

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by blcr11
Wed Feb 20, 2008 9:11 pm
 
Forum: Molecular Biology
Topic: Identify the nucleic acid!
Replies: 5
Views: 587

Identify the nucleic acid!

This question is unfair. 1) resistant to digestion with lambda exonuclease: lambda exonuclease has 5' to 3' activity on double stranded DNA so all choices given would be resistant since 3 of them are circular DNA and 1 is RNA; 2) it does not show typical ...

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by Cat
Wed Feb 20, 2008 6:40 pm
 
Forum: Molecular Biology
Topic: Identify the nucleic acid!
Replies: 5
Views: 587

Re: Identify the nucleic acid!

My bet would be on rRNA. The exonuclease in question acts exclusively on ds DNA. The insensitivity to it almost automatically rules out all the other choices because they are all ds DNAs: pBR322 is a standard plasmid; Phage P22 DNA is ds; ...

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by blcr11
Sun Feb 17, 2008 12:16 pm
 
Forum: Molecular Biology
Topic: Identify the nucleic acid!
Replies: 5
Views: 587
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