In molecular biology, XhoI is a type II restriction enzymeEC that recognise the double-stranded DNA sequence CTCGAG and cleaves after C-1.[1] Type II restriction endonucleases (EC) are components of prokaryotic DNA restriction-modification mechanisms that protect the organism against invading foreign DNA. These site-specific deoxyribonucleases catalyse the endonucleolytic cleavage of DNA to give specific double-stranded fragments with terminal 5'-phosphates.