Purification and characterization of Escherichia coli formamidopyrimidine-DNA glycosylase that excises damaged 7-methylguanine from deoxyribonucleic acid

A DNA glycosylase that excises 7-methylguanines with alkali-opened imidazole rings (formamidopyrimidines) from DNA has been purified more than 8000-fold from Escherichia coli cell extracts. The enzyme does not cleave 3-methyladenine, uracil, and intact 7-methylguanine from DNA. In assays containing...

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Bibliographic Details
Published in:Biochemistry (Easton) 1981-09, Vol.20 (18), p.5201-5207
Main Authors: Chetsanga, Christopher J, Lozon, Marie, Makaroff, Christopher, Savage, Laura
Format: Article
Language:English
Subjects:
DNA, Bacterial - metabolism
DNA-Formamidopyrimidine Glycosylase
Escherichia coli - enzymology
Escherichia coli Proteins
Guanine - analogs & derivatives
Guanine - isolation & purification
N-Glycosyl Hydrolases - isolation & purification
N-Glycosyl Hydrolases - metabolism
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Summary:A DNA glycosylase that excises 7-methylguanines with alkali-opened imidazole rings (formamidopyrimidines) from DNA has been purified more than 8000-fold from Escherichia coli cell extracts. The enzyme does not cleave 3-methyladenine, uracil, and intact 7-methylguanine from DNA. In assays containing pyrimidine analogues like oxauracil, 2,4,6-triaminopyrimidine, 2,5,6-triamino-2-hydroxypyrimidine sulfate, formamidopyrimidine, and 5-nitroso-2,4,6-triaminopyrimidine, only the two compounds showed end product inhibition of the enzyme. The enzyme has been named formamidopyrimidine-DNA glycosylase. It has a molecular weight of 30 000 and a Stokes radius of 26.4 A. The enzyme prefers double-stranded to single-stranded DNA and is stimulated by the presence of 0.1 M KCl in the reaction mixture.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00521a016