Abstract
Various oxidative damages, such as thymine glycol (TG), are spontaneously created in DNA. These damaged bases are mainly repaired by base excision repair pathway. It has been reported that mNTH1 and mNEIL1 may participate actively in the repair process. Although both enzymes possess bifunctional activities of TG-DNA glycosylase and AP lyase, we have found a novel monofunctional DNA glycosylase activity toward TG-DNA in the nuclei of various mouse organs. We have previously reported the purification of the activity from murine stomach with hydrophobic, hydroxyapatite and ion exchange column chromatography. In the experiment, the monofunctional activity could not separate completely from minor bifunctional activity. We have developed a new method to differentially extract the intranuclear target activity from murine lung. The prepared nuclear extract fraction showed the target activity with little bifunctional activity. In the previous experiment, we detected mNEIL1 as one of the candidate proteins having the target activity. At present, two mNEIL1 isoforms and one putative one are known. mNEIL1 itself (NCBI : NP082623) may not be the target protein because of the reported bifunctional activity and the chromatographic behavior. The investigation on the activity of the other isoforms is in progress.
