[Site-specific endonuclease CauB31 from Chloroflexus aurantiacus B3]. / Sait-spetsificheskaia éndonukleaza CauB31 iz Chloroflexus aurantiacus B3.

A sequence-specific endonuclease CauB3I has been isolated from cell extracts of Chloroflexus aurantiacus and partially purified by chromatography on heparin-sepharose; the yield was 3000 units per 1 g of cells. The final preparation is free of non-specific nucleases. It is shown that endonuclease CauB3I recognizes 5' T decreases CCGGA 3' sequence in double-stranded DNA and cleaves it as shown by an arrow. Methylation of adenine in the recognition sequence makes it resistant to CauB3I.