FIG. 6.

Hypothetical function of AidB. On the basis of its FAD cofactor and its ability to bind to methylated DNA, AidB might function as a methylated base dehydrogenase. The Schiff's base product would hydrolyze to release the free base plus formaldehyde, and the reduced flavin could either react with oxygen to produce hydrogen peroxide (as shown) or transfer electrons to another suitable electron acceptor. Analogous chemistry is possible for demethylation of bases alkylated at certain oxygen atoms.