Including a TEV cleavage site between an affinity tag and the protein allows the affinity tag to be removed after purification. This is often desired to assure that the tag does not interfere with the activity of the protein, and because the the tag can interfere with crystallization. Other specific protease sites can also be introduced, such as enterokinase and thrombin.

I see, thanks sir

Hi there,

TEV protease is preferable because it is much more specific than other usual proteases:

https://www.oxfordgenetics.com/SiteContent/TeamResources/cleavage-tag-guide