[Modifying methylase SsoI from Shigella sonnei 47 cells].

A simple and fast method for isolation and purification of SsoI methylase from the bacterial strain Shigella sonnei 47 has been proposed. The enzyme is a modifying component of host cell specificity system and protects the acceptor DNA from hydrolysis by restriction endonucleases SsoI and EcoRI. The method is based on the hydrophobic chromatography of ammonium sulphate fraction on the phenylsepharose. The enzyme preparation obtained is devoid of specific and nonspecific endonucleases traces and is stable at storage in 30% glycerol during a year. The conditions of manifestation of "stroke" activity by the enzyme were studied.