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Interaction between proflavine and chemically methylated deoxyribonucleic acid

1972; Elsevier BV; Volume: 281; Issue: 1 Linguagem: Inglês

10.1016/0005-2787(72)90184-0

1879-3002

Jean Ramstein, M. Leng,

Molecular Sensors and Ion Detection

The binding of proflavine to Micrococcus lysodeikticus DNA and chemically methylated M. lysodeikticus DNA has been studied by several techniques such as absorption, circular dichroism, fluorescence and viscosity (the methylation occurs mainly on the N7 of the guanine residues). The study was limited to the complex of greater affinity (large values of the ratio phosphate/dye). Similarity of the results for the complexes with DNA and methylated DNA indicates that proflavine is also intercalated in the methylated DNA lattice. However, the apparent equilibrium constant is increased by the methylation of DNA. The fluorescence of proflavine bound to methylated DNA is enhanced when compared to free proflavine fluorescence, and can be quenched by iodide ions. The fluorescence of 7-methylguanine residues in “native” methylated DNA is also quenched by iodide ions. Viscosity on sonicated DNA and methylated DNA shows that the length increase on binding proflavine is significantly larger with methylated DNA than with DNA. Some results are given on the complexes between proflavine and poly(A) at acidic pH, methylated poly(A), also poly(G) · poly(C) and methylated poly(G) · poly(C). This study shows that the location of the bound dye depends on the base composition of DNA.