BtrI, a novel restriction endonuclease, recognises the non-palindromic sequence 5′-CACGTC(-3/-3)-3′

The recognition sequence and cleavage positions of a new restriction endonuclease BtrI isolated from Bacillus stearothermophilus SE-U62 have been determined. BtrI belongs to a rare type IIQ of restriction endonucleases, which recognise non-palindromic nucleotide sequences and cleave DNA symmetrically within them.