Effect of Chemical Modification on the Rate of Renaturation of Deoxyribonucleic Acid. Deaminated and Glyoxalated Deoxyribonucleic Acid

Two model systems for DNA base mismatching have been studied. Deaminated DNA was investigated as a model for mismatches other than a purine–purine mismatch. Glyoxalated DNA was studied as a model for the purine–purine case. The melting temperature of glyoxalated DNA is found to be decreased by 1.1 ± 0.2° per mol of glyoxal bound per 100 base pairs. The renaturation rate of deaminated DNA is reduced by a factor of 2 when the melting temperature is lowered by 23°, corresponding to 33% mismatching. The renaturation rate of glyoxalated DNA is reduced by a factor of 2 when the melting temperature is lowered by 17°, corresponding to 16% mismatching. A theory is derived for modified DNA which accounts for the observed results.