Isoschizomers

Isoschizomers

• Restriction endonucleases that recognize the same (similar) sequence are isoschizomers.

Sal I site Xho I siteG>TCGAC C>TCGAG

Cloning strategy using restriction enzymes that are isoschizomers

Ligate

pBluescript (3000bp) Xho I

Sal I

Sal I

Lux operon

(9000bp)

Lu

x op

eron

Digest genomic with Sal I

Digest plasmid with Xho I

pBluescript (3000bp)

Sal I site Xho I siteG>TCGAC C>TCGAG

Enzymes that are isoschizomers create compatible cloning fragments

5’-G-OH p-TCGAC-3’3’-CAGCT-p OH-G-5’

5’-C-OH p-TCGAG-3’3’-GAGCT-p OH-C-5’

5’-GTCGAG-3’3’-CAGCTC-5’

5’-CTCGAC-3’3’-GAGCTG-5’

(Ligation of Fragments)

Sal I site Xho I siteG>TCGAC C>TCGAG

The Sal I-Xho I ligation creates unrecognizable sequences

5’-GTCGAG-3’3’-CAGCTC-5’

5’-CTCGAC-3’3’-GAGCTG-5’

The ligation of Sal I site to an XhoI site results in the formation of a new site that is no longer recognized by either enzyme.

Xho I and Sal I sites are no longer present in the recombinant plasmid

Ligate

pBluescript (3000bp) Xho I

Sal I

Sal I

Lux operon

(9000bp)

Lu

x op

eron

Digest genomic with Sal I

Digest plasmid with Xho I

pBluescript (3000bp)

X

X

Xho I and Sal Iare destroyed

X