Journal Article

DNA modifications by the mutagen glyoxal: adduction to G and C, deamination of C and GC and GA cross-linking.

H Kasai, N Iwamoto-Tanaka and S Fukada

in Carcinogenesis

Volume 19, issue 8, pages 1459-1465
Published in print August 1998 | ISSN: 0143-3334
Published online August 1998 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/19.8.1459
DNA modifications by the mutagen glyoxal: adduction to G and C, deamination of C and GC and GA cross-linking.

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The mutagen glyoxal was reacted with DNA or deoxynucleosides under physiological conditions (pH 7.4, 37 degrees C) in vitro and the products were analyzed by HPLC coupled with a photodiode array UV detector. The efficient formation of a cyclic glyoxal-dG adduct (dG+) was observed in DNA, as well as with dG. The monomeric dG + was gradually decomposed to dG at pH 7.4 and 37 degrees C (t1/2 14.8 h). However, the dG+ formed in single- and double-stranded DNA was rather stable under physiological conditions and the half-lives were 19 and 40 times longer respectively than that of the monomer (t1/2 285 and 595 h respectively). By reaction of glyoxal with deoxycytidine (dC), the deamination products deoxyuridine and 5-hydroxyacetyl-dC (dC+) were formed. Under the same conditions, 5-methyl-dC was deaminated to dT at a higher rate. Deoxyuridine was also formed in DNA by glyoxal treatment. When glyoxal was reacted with various combinations of deoxynucleosides for a prolonged period, dG-glyoxal-dC (GgC), dG-glyoxal-dA (GgA), dG-glyoxal-dG (GgG) and dC-glyoxal-dC (CgC) cross-links were detected, although structures were not assigned unequivocally. Among these, the former two, the GC and GA cross-links, were detected in glyoxal-treated DNA. The yields of these products in DNA were in the following order; dG+ > dU > GgA > GgC > dC+. These DNA modifications may be relevant to glyoxal-induced mutations at GC pairs.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

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