Proteins repair alkylation damage to DNA. The <taxon tax_id="562">Escherichia coli</taxon> alkB gene product protects against cell killing by S(N)2-alkylating agents through DNA repair by a novel direct reversal DNA repair mechanism: the oxidative demethylation of N1-methyladenine or N3-methylcytosine DNA lesions. This reaction occurs on both single- and double-stranded DNA, and requires AlkB-bound non-heme Fe(2+), O(2) and alpha-ketogluterate to oxidize the offending methyl group. This is followed by the release of succinate, CO(2) and formaldehyde, and the restoration of undamaged A or C in DNA [<cite idref="PUB00010126"/>]. Alkylated DNA repair protein AlkB