title: DNA glycosylase activities for thymine residues damaged by ring saturation, fragmentation, or ring contraction are functions of endonuclease III in Escherichia coli.
abstract: A DNA glycosylase activity that excises oxidized, fragmented thymine residues from a polydeoxyribonucleotide has been purified 9,500-fold to apparent homogeneity from Escherichia coli. The purified enzyme also excises thymine glycol and cleaves DNA at apurinic sites, and appears to be identical with E. coli DNA endonuclease III. The enzyme catalyzes the release of several different forms of oxidized thymine, including urea, methyltartronylurea and 5-hydroxy-5-methylhydantoin. The molecular weight of the native protein is 25,000, and the same value is obtained for the denatured homogeneous protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
mesh_terms: D045647:DNA Glycosylases; D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D013941:Thymine / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D013941:Thymine