[Fractionation and purification of DNA methylation enzymes from Escherichia coli CK cells on phosphocellulose P-11].

Conditions for purification and fractionation of the methylases from E. coli CK cells using phosphocellulose P-11 were studied. A fraction, obtained after ammonium sulphate precipitation, was used as a starting preparation for column chromatography. Elution was carried out with linear gradient of NaCl concentration from O to 0.8 M. The methylase activity was found in effluent fractions, in rinsing solutions and in the gradient zone (G). The fractions, unadsorbed on P-11, contained methylases of adenine and cytosine. In the experiments with the gradient elution the methylase activity was observed in fractions, corresponding to NaCl concentration of 0.12, 0.18, 0.26, 0.33 and 0.68 M. The specific activity was increased 10-4O-fold in the fraftions during the purification. The G1, G2, and G5 fractions contained only the adenine methylase and did not possess the cytosine-methylating activity. A mixture of enzymes, methylating adenine and cytosine, was found in G3 and G4 fractions. The data obtained suggest that several methylases are present in E. coli CK cells; these enzymes exist apparently as isoenzymes.