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en:restriction-modification_system [2013/06/09 10:10] (current)
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 +======Restriction-modificaton system======
 +=====TypeI R-M system=====
 +The hsd(host specificity defective) consists of flanking genes of hsdR, hsdM and hsdS, they have function of restriction,​ modification and recognition,​ respectively.
 +
 +====Properties====
 +  *Hetero complex enzyme consisting of 3 subunits
 +  *Modification system have a methyltransferase activity that requires [[S-Adenosylmethionine]] as a donor of methyl group.
 +  *Restriction system requires [[ATP]] and [[Mg]]<​sup>​2+</​sup>​.
 +  *The site of recognition is distant from that of digestion.
 +
 +=====TypeII R-M system=====
 +Commercially available restriction enzymes belong to TypeII restriction-modification system. They can cut dsDNA without its associating methylase.
 +
 +
 +====Properties====
 +  *Restriction subunit and modification subunit are acitive itself.
 +  *Restriction system requires [[Mg]]<​sup>​2+</​sup>​.
 +  *Restriction system cuts within its recognition site.
 +
 +
 +====Reactions====
 +**producing blunt ends**\\ ​
 +
 +{{:​re_smai_subs.png|SmaI substrate }}
 + ​-->​ {{:​re_smai_frg1.png|SmaI fragment 1}} + {{:​re_smai_frg2.png|SmaI fragment 2}}
 +
 +
 +**producing 5'​-sticky ends**\\ ​
 +
 +{{:​re_ecori_subs.png|EcoRI substrate }}
 + ​-->​ {{:​re_ecori_frg1.png|EcoRI fragment 1}} + {{:​re_ecori_frg2.png|EcoRI fragment 2}}
 +
 +
 +**producing 3'​-sticky ends**\\ ​
 +
 +{{:​re_psti_subs.png|PstI substrate}}
 + ​-->​ {{:​re_psti_frg1.png|PstI fragment 1}} + {{:​re_psti_frg2.png|PstI fragment 2}}
 +
 +/*
 +
 +Images were created by [[:​cmaster/​en/​Restriction_enzyme_reaction|ConstructMaster]].
 +
 +
 +C.Master is not available..
 +
 +*/
 +
 +
 +
 +======Reference======
 +
 +  *{{pubmed>​long:​10839821}}
 +
 +
 +