High-pressure study of dye–DNA interaction

Pressure-dependent satellite hole spectra of 4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a, 4a-diaza-s-indacene-8-propionic acid, succinimidyl ester (BP493) and its covalent link to a ten bases of thymidine deoxyribonucleotides, d(T10), doped in glycerol:water glasses have been examined. Pressure-induced frequency shifts of the absorption bands show that the compressibility is larger in d(T10) than in matrix. However, two sets of non-resonant holes observed in the satellite hole spectra of BP493 upon covalent attachment to d(T10) indicate that there are two different conformational structures of BP493-d(T10) adducts. Moreover, the surrounding d(T10) in two different conformational structures of BP493-d(T10) adducts changes the frequency shifts in opposite direction with respect to the magnitudes of the pressure-induced frequency shifts of the vibrons of BP493 in glasses. In addition, our data suggest that different shifts of various vibrons are mainly determined by the degrees of compression at different dimensions.