Fig. 2.

Cleavage of a THF lesion and an AP site in free and nucleosomal bound DNA. (A) Cleavage of an AP site site by purified Fpg. (B) Cleavage of an AP site site by purified Nth. (C) Cleavage of an AP site site by purified APE1. (D) Cleavage of a THF lesion by purified APE1. (E) Cleavage of a THF lesion by CHO-K1 nuclear extract. (Square) free DNA, (triangle) nucleosomal-bound DNA. For each experiment, the background has been subtracted from the data prior to normalization to 100%. Error bars represent standard deviation determined from at least three independent experiments.