Editing Restriction enzyme (section)

{{Short description|Class of enzymes that divide DNA}}
{{Restriction enzyme glossary}}

A '''restriction enzyme''', '''restriction endonuclease''', '''REase''', '''ENase''' or'' '''restrictase''' '' is an [[enzyme]] that cleaves [[DNA]] into fragments at or near specific recognition sites within molecules known as [[restriction site]]s.<ref name="pmid795607">{{cite journal | vauthors = Roberts RJ | title = Restriction endonucleases | journal = CRC Critical Reviews in Biochemistry | volume = 4 | issue = 2 | pages = 123–64 | date = November 1976 | pmid = 795607 | doi = 10.3109/10409237609105456 }}</ref><ref name="pmid2172084">{{cite journal | vauthors = Kessler C, Manta V | title = Specificity of restriction endonucleases and DNA modification methyltransferases a review (Edition 3) | journal = Gene | volume = 92 | issue = 1–2 | pages = 1–248 | date = August 1990 | pmid = 2172084 | doi = 10.1016/0378-1119(90)90486-B }}</ref><ref name="isbn0-89603-234-5">{{cite book |vauthors=Pingoud A, Alves J, Geiger R | editor = Burrell M | title = Enzymes of Molecular Biology | publisher = Humana Press | location = Totowa, NJ | series= Methods of Molecular Biology | volume= 16 | year = 1993 | pages = 107–200 | chapter = Chapter 8: Restriction Enzymes | isbn = 0-89603-234-5}}</ref>   Restriction enzymes are one class of the broader [[endonuclease]] group of enzymes. Restriction enzymes are commonly classified into five types, which differ in their structure and whether they cut their DNA [[enzyme substrate (biology)|substrate]] at their recognition site, or if the recognition and cleavage sites are separate from one another. To cut DNA, all restriction enzymes make two incisions, once through each [[backbone chain|sugar-phosphate backbone]] (i.e. each strand) of the [[DNA double helix]].

These enzymes are found in [[bacteria]] and [[archaea]] and provide a defense mechanism against invading [[virus]]es.<ref name="pmid4897066">{{cite journal | vauthors = Arber W, Linn S | title = DNA modification and restriction | journal = Annual Review of Biochemistry | volume = 38 | pages = 467–500 | year = 1969 | pmid = 4897066 | doi = 10.1146/annurev.bi.38.070169.002343 }}</ref><ref name="pmid6314109">{{cite journal | vauthors = Krüger DH, Bickle TA | title = Bacteriophage survival: multiple mechanisms for avoiding the deoxyribonucleic acid restriction systems of their hosts | journal = Microbiological Reviews | volume = 47 | issue = 3 | pages = 345–60 | date = September 1983 | pmid = 6314109 | pmc = 281580 | doi = 10.1128/MMBR.47.3.345-360.1983 }}</ref> Inside a [[prokaryote]], the restriction enzymes selectively cut up ''foreign'' DNA in a process called ''restriction digestion''; meanwhile, host DNA is protected by a modification enzyme (a [[methyltransferase]]) that [[DNA methylation|modifies]] the prokaryotic DNA and blocks cleavage. Together, these two processes form the [[restriction modification system]].<ref name="pmid11557807">{{cite journal | vauthors = Kobayashi I | title = Behavior of restriction-modification systems as selfish mobile elements and their impact on genome evolution | journal = Nucleic Acids Research | volume = 29 | issue = 18 | pages = 3742–56 | date = September 2001 | pmid = 11557807 | pmc = 55917 | doi = 10.1093/nar/29.18.3742 }}</ref>

More than 3,600 restriction endonucleases are known which represent over 250 different specificities.<ref>{{cite journal | vauthors = Roberts RJ | title = How restriction enzymes became the workhorses of molecular biology | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 102 | issue = 17 | pages = 5905–8 | date = April 2005 | pmid = 15840723 | pmc = 1087929 | doi = 10.1073/pnas.0500923102 | bibcode = 2005PNAS..102.5905R | doi-access = free }}</ref> Over 3,000 of these have been studied in detail, and more than 800 of these are available commercially.<ref name="pmid17202163">{{cite journal | vauthors = Roberts RJ, Vincze T, Posfai J, Macelis D | title = REBASE--enzymes and genes for DNA restriction and modification | journal = Nucleic Acids Research | volume = 35 | issue = Database issue | pages = D269-70 | date = January 2007 | pmid = 17202163 | pmc = 1899104 | doi = 10.1093/nar/gkl891 }}</ref> These enzymes are routinely used for DNA modification in laboratories, and they are a vital tool in [[molecular cloning]].<ref name="isbn0-632-03712-1">{{cite book | vauthors = Primrose SB, Old RW | title = Principles of gene manipulation: an introduction to genetic engineering | publisher = Blackwell Scientific | location = Oxford | year = 1994 | isbn = 0-632-03712-1 | url = https://archive.org/details/principlesofgene00oldr }}</ref><ref name="isbn0-8053-3040-2">{{cite book |vauthors=Micklos DA, Bloom MV, Freyer GA | title = Laboratory DNA science: an introduction to recombinant DNA techniques and methods of genome analysis |publisher = Benjamin/Cummings Pub. Co | location = Menlo Park, Calif | year = 1996 | isbn = 0-8053-3040-2}}</ref><ref name="isbn1-55581-176-0">{{cite book |vauthors=Massey A, Kreuzer H | title = Recombinant DNA and Biotechnology: A Guide for Students | publisher = ASM Press | location = Washington, D.C. | year = 2001 | isbn = 1-55581-176-0}}</ref>