Isolation and characterisation of restriction endonuclease BcuAI from Bacillus cereus A

Restriction endonuclease BcuAI, an isoschizomer of AvaII, has been purified from Bacillus cereus A. The procedure of isolation of BcuAI included the fractionation with ammonium sulfate and column chromatography on DEAE-Sepharose (elution buffer 10 mM K-phosphate, pH 7.4, 0.1 mM EDTA, 1 mM DTT, 0.0-1.0 M KCl; elution zone of enzyme activity 0.2-0.3 M KCl). 1400 u. BcuAI can be obtained from 1 g. of wet cells. BcuAI showed maximal activity at 30-37 degree C, pH between 7.6-8.2, MgCl sub(2) concentration in the range of 5-10 mM and at high ionic strength.