Further purification and characterization of human 3-methyladenine-DNA glycosylase. Evidence for broad specificity.
Further purification of a human placental 3-methyladenine-DNA glycosylase by phosphocellulose column chromatography yielded a 6000-fold increase in specific activity with greater than 5% recovery. Although 3-methyladenine was the predominant base released from double-stranded methylated DNA by this enzyme, minor releasing activities for 7-methylguanine and 3-methylguanine were also observed. During purification, the three DNA glycosylase activities consistently copurified with constant ratios of specific activity. Moreover, all the activities were heat-inactivated at 50 degrees C at the same rate, required double-stranded methylated DNA as substrate, were inhibited by spermine and spermidine, and were not subject to product inhibition. These data strengthen the likelihood that the three activities are associated with a single DNA glycosylase.
D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D045647:DNA Glycosylases; D004355:Drug Stability; D005260:Female; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013379:Substrate Specificity
D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C076131:DNA-3-methyladenine glycosidase II