DNA glycosylases are able to remove bases from DNA by hydrolysing the glycosidic bond between the ribose sugar and the base. This enables specific glycosylases to correct particular defects in DNA such as mispairing or the insertion of a base analogue, making them of particular interest towards an understanding of DNA repair in cells. 3-methyladenine DNA glycosylase I is able to recognise the cationic base 3-methyladenine and remove it wherever it occurs in the sequence. As part of the HhH-GPD superfamily of DNA glycosylases, which includes well characterised members such as MutY, it works by a monofunctional mechanism to remove a purine, resulting in a relatively low rate enhancement of between 10 and 20 times the rate of spontaneous hydrolysis. Unlike other glycosylases that have a HhH motif, 3-methyladenine DNA glycosylase I does not have a conserved aspartate, indicating an alternative base excision mechanism is in place.