Restriction Enzyme

Restriction Enzyme is a biological scissor to cut DNA into short fragments.
Its 4 types.
Applications

1. RESTRICTION ENZYMES Presented by: Fizza Mehwish Department of Biotechnology University of Science & Technology, Bannu

2. Restriction Enzymes Also called restriction endonuclease. Identifies specific Recognition sites. Molecular scissors that cuts DNA only at that specific sites. Found naturally in prokaryotes as a defense mechanism. A useful tool in DNA modification and manipulation.

3. Brief History

4. Types of Restriction Enzymes Restriction enzymes are categorized into four general groups. Type I V Restriction enzymes

5. Type I Restriction enzymes Type I restriction enzymes (REases) are large pentameric proteins with separate restriction (R), methylation (M) and DNA sequence-recognition (S) subunits. It possesses a cleaving site which is 1000 bp away from the recognition site. It requires both ATP and S-adenosyl-L-methionine cofactors to function. Examples; EcoK I , EcoA I , CfrAI

6. Type II Restriction enzymes Type II Restriction enzymes are components of restriction and modification systems that protect bacteria and archea against invading foreign DNA. Most are or tetrametric enzymes that cleaves DNA at defined sites of 4-8 bp in length at which they recognize it. It requires Mg2+ cofactor for catalysis. Examples ; EcoR I, Hind III, BamH I

7. Type III Restriction enzymes Type III Restriction enzymes are hetero-oligomeric multifunctional proteins composed of two subunits nuclease subunit and a dimeric methyltransferase subunit that binds only one specific DNA. It recognize two separate non-palindromic sequences that are inversely oriented but cleave DNA at random sequences aprox. 25 bp from the recognition sequence. It requires both Mg2+ ion and S-adenosyl-L-methionine cofactors. Examples ; EcoP I, Hinf III, EcoP 15 I

8. Type IV Restriction enzymes Cleave only normal and modified DNA (methylated, hydroxymethylated, and glycosyl-hydroxymethylated bases). Recognition sequences have not been well defined, cleavage take place 30 bp away from one of the sites. It requires Mg2+ ion cofactor. Examples ; McrBC, GmrSD

9. Nomenclature.. Each enzymes is named after the bacterium from which it was isolated, using a naming system based on; Bacterial genus Species Strain Order of identification Example;