Idnetification of DNA methylases in Escherichia coli CK cells
Nikol'skaia, I.I.; Vanioshin, B.F.
Biokhimiia 40(5): 1081-1086
1975
ISSN/ISBN: 0320-9725 PMID: 764884 Document Number: 88595
E. coli CK contains a methylase which catalyzes the incorporation of CH-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. The methylase was active in phosphate and Tris HCl buffers, pH 6.5-7.5, and did not require Mg2+, EDTA and dithiotreithol. The enzyme recognizes certain nucleotide sequences in all the DNAs studied and has a wider specificity, compared to the enzyme from E. coli B. The methylase from E. coli CK developed the highest activity with thumus DNA. A methylase from rat liver nuclei was inactive with bacteriophage DNA.