Thirteen bacterial DNA methyltransferases that catalyze the formation of 5-methylcytosine within specific DNA sequences possess related structures. Similar building blocks (motifs), containing invariant positions, can be found in the same order in all thirteen sequences. Five of these blocks are highly conserved while a further five contain weaker similarities. One block, which has the most inv...

The major photoproduct formed between benzo[a]pyrene and thymine is identified as 1-(benzo[a]pyren-6-yl)-thymine by means of spectroscopic analysis and isotopic syntheses. Irradiation of 1-methylcytosine hydrochloride and anthracene gives two isolable photoproducts of which one is assigned the structure 5-(anthracen-9-yl)-1-methylcytosine.

The DNA base composition, including the minor base content, of 26 strains of bacteria was determined. The studied bacteria are sources of widely used restriction endonucleases. Approximately 35% of the bacterial DNAs contained N4-methylcytosine, about 60% contained 5-methylcytosine, and about 90% had N6-methyladenine.

Mutation in p53 tumor suppressor gene is a hallmark of human cancers. Six major mutational hotspots in p53 contain methylated CpG (mCpG) sites, and C -->T transition is the most common mutation at these sites. It was hypothesized that the formation of 5-methylcytosine glycol induced by reactive oxygen species, its spontaneous deamination to thymine glycol and the miscoding property of the latte...