FIG. 4.

The methylation of CpG sites in synthetic duplexes does not affect the glycosylase activity of MBD4. Urea-denaturing PAGE analysis of the glycosylase activity was carried out with methylated and unmethylated versions of the 60-bp DNA fragment. An approximately 20 nM concentration of the 60-bp heteroduplex DNA was incubated with 50 nM MBD4 for various lengths of time. Reactions were run on a denaturing gel, and DNA species were detected by infrared scanning. Results are expressed as the percentage of cleavage.