Purification and characterization of the sequence-specific endonuclease Bam HI.

The specific endonuclease Bam HI from Bacillus amyloliquefaciens (RUB 500) has been purified to apparent homogeneity. Two active forms of the enzyme corresponding to the dimeric and tetrameric forms have been isolated. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme dissociated into Mr = 22,000 +/- 500 subunits. Bam HI has a broad pH optimum on the alkaline side and requires Mg2+ which can be partially replaced by Mn2+. The enzyme catalysis appears to be governed by a two-step mechanism.