Purification and properties of theMboll, a class-IIs restriction endonuclease

After five purification steps a homogeneous preparation of endonuclease MboII was obtained, and several properties of the enzyme were determined. MboII is a monomer, with Mr under native and denaturing conditions being 47-49 x 10(3) Da. Endonuclease MboII is a basic protein (pI 8.3) which remains active when Mg2+ is replaced by Mn2+, Co2+, Ca2+, or Fe2+. MboII exhibits a star activity in the presence of some of the following reagents or ions: DMSO, glycerol, ethanol (and Co2+ or Mn2+ at pH 6). MboII does not bend DNA and is heat sensitive, losing activity after 15 min at 50 degrees C.