Isolation and characterization of site-specific endonuclease Bsp123 I from thermophilic strain Bacillus species 123.

The preparation of site-specific endonuclease Bsp123 I was isolated and purified from the thermophilic strain Bacillus species 123. Endonuclease Bsp123 I recognizes the sequence CGCG and cleaves it in the middle between nucleotides G and C, producing blunt ends. Thus, Bsp123 I is an isoschizomer of FnuDII. The maximal activity of the enzyme is displayed at 42 degrees C, pH 8.0, 100 mM NaCl, 10 mM MgCl2.