AAG and AlkA protect abasic DNA in a duplex from PFBHA. Reactions of duplex 2/3 (A), single stranded 2 (B), and duplex 2/4 (C) contained 0.25 µM DNA, 1.5 mM PFBHA, and 1.5 µM AAG, 1.5 µM AlkA, or no added enzyme. Samples from reactions performed at 37 °C and pH 6.5 were reduced with NaBH4 prior to separation on 20% denaturing polyacrylamide gels. Exponential fits to the data are shown, and kobs values from the fits are recorded in Table 1.