PURIFICATION AND CHARACTERIZATION OF THE NUCLEASE NUCM OF ERWINIA-CHRYSANTHEMI

The major periplasmic nuclease of Erwinia chrysanthemi strain 3937, Nu cM, has been purified near to homogeneity by a one step purification p rocedure, using chromatography on a sulfopropyl column. NucM cleaves r andomly single and double-stranded DNA and RNA. It does not need dival ent cations for its action, and is more active in low salt buffers. A serine and a histidine residue could be present in the catalytic site. Formation of disulfide bonds is necessary for NucM activity. NucM is probably synthesized as a reduced inactive polypeptide and becomes act ive in the periplasm once disulfide bonds are formed.