[Isolation of site-specific endonucleases and methylases from Bacillus cereus 83].

The site-specific endonuclease R Bce83I and methylase M Bce83I were isolated from Bacillus cereus 83 by three consecutive chromatographies on blue agarose, hydroxyapatite and heparin-Sepharose. R Bce83I recognizes [formula: see text] sequences on the DNA and cleaves the DNA as indicated by the arrows. The endonuclease is stimulated by S-adenosyl-L-methionine and may consequently be referred to type IV restriction enzymes.