Both Purified Human 1,N6-Ethenoadenine-Binding Protein and Purified Human 3-Methyladenine-DNA Glycosylase Act on 1,N6-Ethenoadenine and 3-Methyladenine

We previously described a protein, isolated from human tissues and cells, that bound to a defined double-stranded oligonucleotide containing a single site-specifically placed 1, N6-ethenoadenine. It was further demonstrated that this protein was a glycosylase and released 1,N6-ethenoadenine. We now find that this enzyme also releases 3-methyladenine from methylated DNA and that 3-methyladenine-DNA glycosylase behaves in the same manner, binding to the ethenoadenine-containing oligonucleotide and cleaving both ethenoadenine and 3-methyladenine from DNA containing these adducts. The rate and extent of glycosylase activities toward the two adducts are similar.