[Isolation and purification of restriction endonuclease PmiI from Proteus mirabilis 1667].

A new restriction endonuclease Pmi I was detected in Proteus mirabilis 1667. The enzyme hydrolyzes DNA of the phage lambda into 10 electrophoretically separating fragments with molecular weights of 1.3-7.9 mD. With the use of two-stage chromatography on blue sepharose and phosphocellulose it is possible to obtain restriction endonuclease Pmi I free of the admixtures of ballast proteins, nonspecific nucleases and phosphatases.