[Idnetification of DNA methylases in Escherichia coli CK cells]

E. coli CK cell are found to contain metylase which catalyses the incorporation of CH33-groups into tissue and phage DNAs in vitro in the presence of S-adenosyl-L-methionine, the donor of methyl groups. The enzyme was precipitated by (NH4)2SO4 of 30-60% saturation, which increased its specific activity in 1.9 times. Metylase was active both in phosphate and Tris. HCl buffers, pH 6.5-7.5 and did not require Mg2+, EDTA and dithiotreithol. The enzyme recognises certain nucleotide sequences in all the DNAs studied and has more wide specificity as compared with the enzyme from E. coli B. Methylase from E. coli CK developed the highest activity with thymus DNA. Methylase from rat liver nuclei turned to be inactive with bacteriophage DNA.