[Isolation and properties of BstBSI restriction endonuclease from the thermophilic soil bacteria Bacillus stearothermophilus BS].

A new restriction endonuclease BstBSI was isolated and purified from the thermophilic soil bacterium Bacillus stearothermophilus BS by the blue sepharose and hydroxyapatite chromatographies. The enzyme is an isoschizomer of SnaI from Sphaerotilus natans C. It recognizes the hexanucleotide GTATAC and cleaves DNA in the center of the sequence. The maximal catalytic activity of the endonuclease is registered in 50 mM tris-HCl (pH 9.0) buffer with the high ionic strength (100 mM NaCl) in the presence of 10 mM MgCl2 at 45 degrees C. Glucosylated DNA of the phage T4 is not cleaved by the enzyme.