Figure 4.

Comparative activity on different 8-oxoG-containing mismatches in extracts from ogg1 null mice. Nuclear extracts prepared from testes of wild-type (+/+), heterozygous (+/−), and ogg1 null (−/−) mice were incubated with double-stranded oligonucleotide substrates containing different residues opposite 8-oxoG (as indicated). The assay was as in Fig. 2, except, in this case, a 22-bp substrate was used and OGG1 activity is indicated by cleavage of the ³²P-labeled 8-oxoG-containing strand to produce a 9-nt species.