title: Detection of different types of damage in alkylated DNA by means of human corrective endonuclease (correndonuclease).
abstract: Corrective endonuclease (correndunclease) activity of HeLa cells was assayed with alkylated DNA. Double-stranded, covalently closed DNA from phage PM II was treated with methyl methanesulfonate, N-methyl-N-nitrosourea, beta-propiolactone, or diepoxybutane to introduce alkylated bases and alkali-labile sites into the DNA. The damaged DNA was incubated with an extract of HeLa cells that catalyzes the formation of breaks at apurinic sites in double-stranded DNA. Methylated DNA was broken at every alkali-labile site by the HeLa correndonuclease, which indicated that these sites are similar to the apurinic sites produced by heating at acid pH. DNA alkylated with beta-propiolactone or diepoxybutane containing the same number of alkali-labile sites was broken to a far lesser extent. This indicates the presence of a second type of alkali-labile damage that is correndonuclease-insensitive.
mesh_terms: D000477:Alkylating Agents; D001435:Bacteriophages; D002073:Butanes; D004260:DNA Repair; D004279:DNA, Viral / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D004852:Epoxy Compounds; D006367:HeLa Cells / Q000201:enzymology; D008741:Methyl Methanesulfonate; D009607:Nitrosourea Compounds; D011420:Propiolactone
chemical_list: D000477:Alkylating Agents; D002073:Butanes; D004279:DNA, Viral; D004852:Epoxy Compounds; D009607:Nitrosourea Compounds; D011420:Propiolactone; D008741:Methyl Methanesulfonate; D003851:Deoxyribonucleases; D004720:Endonucleases