title: Size of the directing moiety at carbon 5 of cytosine and the activity of human DNA(cytosine-5) methyltransferase.
abstract: M13 DNAs in which carbon 5 of each deoxycytidine residue in one strand is replaced with a bulky group are very good substrates for human DNA (cytosine-5) methyltransferase. Rate enhancements of up to 35 fold are obtained depending on the size of the moiety at C-5. The enzyme appears optimally suited to sense a methyl group in one strand at this position. Alkaline density gradient analyses of the distribution of methyl groups applied to 5-BrdCyd or 5-IdCyd substituted DNA reveal that these groups serve to direct the enzyme to methylate the unsubstituted strand.
mesh_terms: D003596:Cytosine / Q000031:analogs & derivatives*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D004262:DNA Restriction Enzymes; D006801:Humans; D007700:Kinetics; D013379:Substrate Specificity
chemical_list: D003596:Cytosine; D004248:DNA (Cytosine-5-)-Methyltransferases; D004262:DNA Restriction Enzymes