FIGURE 4.

Glycosylase assay of the cross-linked complexes. To test the glycosylase activity of the cross-linked complex used in SAXS, we labeled the target strand (A strand), which contains the disulfide cross-linker with ³²P and annealed it to the complimentary strand containing either an oxoG or a T that pairs with the A. The annealed DNA was added to P164C MutY with or without the presence of adenine. The reaction proceeded for 40 h at room temperature before it was quenched by NaOH (see “Experimental Procedures” for detailed procedures). A, a representative urea gel showing cleavage of A opposite oxoG by MutY and lack of cleavage of A opposite T under the same conditions. B, fraction of DNA cleaved in the reactions in A shown in bar diagram. Each data point shows an average of three parallel experiments, and the error bars show the standard deviation from the average.