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Carcinogenesis. 1998 Aug;19(8):1459-65.

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

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Department of Environmental Oncology, University of Occupational and Environmental Health, Kitakyushu, Japan.


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.

[Indexed for MEDLINE]

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