title: The presence of an endonuclease acting on UV-irradiated and depurinized DNA in cells of Micrococcus lysodeikticus.
abstract: Enzymatic activity, hydrolyzing DNA treated with beta-isopropyl-bis-beta-chloroethylamine (HN2-DNA), HN2-DNA exposed at 50 degrees for 1 h, and DNA treated with acid, to acid-soluble fragments was found in extracts from cells of M. lysodeikticus. The endonucleolytic component ofthe indicated activity manifests chromatographic properties on DEAE- and CM-cellulose, close to those for UV-endonuclease. Activity is manifested by UV-irradiated DNA, proflavin, and cyanide. Two electrophoretically homogeneous fractions of UV-endonuclease (after chromatography on DEAE- and CM-cellulose), with molecular weights about 13,000 and 15,000 daltons, exhibit endonucleolytic activity with respect to HN2-DNA, exposed at 50 degrees for 1 h, and with respect to "acid" DNA, treated for 6 min at 70 degrees in citrate buffer, pH 3.5. The activity with respect to the latter substrate is competitively suppressed by UV-irradiated DNA. The most probable substrate of UV-endonuclease, in addition to cyclobutane dimers, is the depurinized region of DNA.
mesh_terms: D001080:Apurinic Acid / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D004269:DNA, Bacterial / Q000528:radiation effects*; D003851:Deoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D005092:Exonucleases / Q000378:metabolism; D007700:Kinetics; D008837:Micrococcus / Q000201:enzymology; D008970:Molecular Weight; D009588:Nitrogen Mustard Compounds; D011830:Radiation Effects; D014466:Ultraviolet Rays
chemical_list: D004269:DNA, Bacterial; D009588:Nitrogen Mustard Compounds; D001080:Apurinic Acid; D003851:Deoxyribonucleases; D004720:Endonucleases; D005092:Exonucleases