Sequence-specific alkali-labile lesions in DNA caused by D-isoglucosamine

The site-specific induction of DNA damage by 1-amino-1-deoxy-D-fructose (D-isoglucosamine) was investigated. When 32P-end-labeled DNA restriction fragments of known sequence were reacted with D-isoglucosamine in the presence of Cu2+, and the DNA products were analyzed on high-resolution denaturing polyacrylamide gels after treatment with aqueous piperidine (1 M) at 90 degrees C for 30 min, the DNA strands were cleaved at pyrimidine residues at a statistically significant frequency, and 80.5% of the extensively damaged sites were induced at pyrimidine residues in dinucleotide sequences of pyrimidine-purine (5'----3'). These cleavages were scarcely observed without piperidine/heat treatment. The damaged DNA sites increased in proportion to the reaction time and concentration of D-isoglucosamine. Metal-chelating agents (EDTA, diethylenetriaminepentaacetic acid) and some oxygen radical scavengers inhibited the induction of alkali-labile lesions. These results indicate that some oxygen radicals are involved in the induction of alkali-labile lesions.