Release of N2,3-ethenoguanine from chloroacetaldehyde-treated DNA by Escherichia coli 3-methyladenine DNA glycosylase II

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

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Document Type



Acetaldehyde; Carbon Radioisotopes; Chromatography, High Pressure Liquid; DNA; *DNA Glycosylases; DNA Repair; Deoxyguanine Nucleotides; Escherichia coli; Guanine; Kinetics; Methylnitrosourea; N-Glycosyl Hydrolases; Time Factors; Tritium


Life Sciences | Medicine and Health Sciences


The human carcinogen vinyl chloride is metabolized in the liver to reactive intermediates which form N2,3-ethenoguanine in DNA. N2,3-Ethenoguanine is known to cause G----A transitions during DNA replication in Escherichia coli, and its formation may be a carcinogenic event in higher organisms. To investigate the repair of N2,3-ethenoguanine, we have prepared an N2,3-etheno[14C]guanine-containing DNA substrate by nick-translating DNA with [14C]dGTP and modifying the product with chloroacetaldehyde. E. coli 3-methyladenine DNA glycosylase II, purified from cells which carry the plasmid pYN1000, releases N2,3-ethenoguanine from chloroacetaldehyde-modified DNA in a protein- and time-dependent manner. This finding widens the known substrate specificity of glycosylase II to include a modified base which may be associated with the carcinogenic process. Similar enzymatic activity in eukaryotic cell might protect them from exposure to metabolites of vinyl chloride.


Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9331-4.

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

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