Restriction Endonucleases

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INTRODUCTION

STRUCTURE

DNA BINDING

CLEAVAGE

REFERENCES

Structure

What Does a Restriction Endonuclease Look Like?

Type II restriction endonucleases can basically be divided into two families: EcoRI-like enzymes and EcoRI like enzymes. Both of these enzyme families have a conserved core of four beta strands and one alpha helix. Because it is a dimer, there are a total of 8 beta-strands and two alpha-helices.


EcoRI Push to see the conserved core	EcoRV Push to see the conserved core Note the large bend in the DNA. This will be discussed on the next page.

Otherwise, these proteins vary in their structure of alpha helices and beta-sheets. The conserved core is evidence of a common ancestor.

Here are some more members of each family. Not all of these have been crystallized yet.