[Separation of modification methylation and restriction enzymes from Shigella sonnei 47].

Two systems for DNA host specificity have been demonstrated for Shigella sonnei cells, SsoI and SsoII. The aim of the present work was to separate the modificating methylases and restriction endonucleases from Shigella sonnei and to study the modificating functions of methylases MSsoI and MSsoII. The possibilities to separate the methylation and restriction enzymes by column chromatography on affine, ionoexchange and hydrophobic sorbents were analyzed. The scheme for separation of methylases and restriction endonucleases of Shigella sonnei was elaborated, consisting of the fractioning of total preparation on phenyl-sepharose and subsequent isoelectrofocusing on ampholines. The modification functions of MSsoI and MSsoII methylases obtained by this technique and devoid of concomitant restriction endonucleases were studied. The in vitro experiments have shown the acceptor DNA methylated by MSsoI or MSsoII to be RSsoI or RSsoII restriction proof.