THE RESTRICTION ENDONUCLEASES FROM BACILLUS

The activities of restriction endonucleases were found in 10 out of 66 strains ofBecillus isolated and examined in our country.These enzymes were partially purifiedand their recognition sequences were characterized.Bsp211Ⅰ,Bsp226Ⅰ and Bce71Ⅰare the isoschizomers of HaeⅢ.Bsp211Ⅰ and HaeⅢ have the same cleavage sitesas indicated by the arrow in the sequence ■.The purification procedureof Bsp211Ⅰ is very simple and its yield is rather high.The recognition sequences ofBsp105Ⅰ,Bsp67Ⅰ,Bsp74Ⅰ and Bsp76Ⅰ are the same as that of MboⅠ,whichrecognizes the sequence ■,the arrow indicating the cleavage sites for Bsp105Ⅰ and Bsp67Ⅰ.While Bsp105Ⅰ does not digest modified DNA,Bsp67Ⅰ digestsDNA whether the adenine residue is methylated or not.Bsp63Ⅰ and Bsp78Ⅰ areisoschizomers of PstⅠ,whose recognition sequence is ■.The cuttingsites of Bsp 63Ⅰ and PstⅠ are identical.