Figure 7.

Time-dependence of dsDNA repair detected by NarI sensitivity. The 6mG-containing 24mer duplex (oligos 4 and 5) 0.037 µM, was dissolved in 40 mM Tris acetate (pH 7.9 at 20°C), 100 mM potassium phosphate, 20 mM magnesium acetate, 2 mM DTT, containing 0.5 mg/ml BSA. To start the reaction, AGT was added to a final concentration of 0.11 µM. Aliquots were withdrawn and quenched in 0.2% SDS after 15 s, 30 s, 45 s, 60 s, 120 s, 180 s, 240 s, 360 s, 900 s, 2400 s and 3600 s (samples b–l, respectively); unrepaired DNA is shown in sample a. Samples were deproteinized by phenol extraction followed by ether extractions as described; they were then digested with NarI (15 U) for 2 h at 37°C and resolved by electrophoresis on a 20% gel.