EXCITED-STATE PROPERTIES OF THYMIDINE AND THEIR RELEVANCE TO ITS HETEROGENEOUS EMISSION IN DOUBLE-STRANDED DNA

摘要: Published results on synthetic polynucleotides point to T as the major emitting fluorophore in DNA. We have reported also that bases of nonalternating polynucleotide poly(dA).poly(dT), which was selectively excited, undergo large-amplitude motions picosecond-nanosecond time scales (S. Georghiou et al., Biophys. J. 70, 1909-1922, 1996). In study, fluorescence decay profile this found contain a number components; these may be considered result give rise distribution stacked geometries varying rigidity well dispersion and polar interactions. Here, we report study undertaken order test hypothesis. To effect, studied photophysical properties thymidine (1) aqueous buffer organic solvents (2) sucrose solutions viscosity extending 149 cP. The suggest quantum yield decreases with an increase polarizability solvent, whereas it increases solvent polarity (on basis empirical parameter ETN) or viscosity. These findings following for DNA: Base stacking two antagonistic effects, namely causes reduction interactions enhancement exposure environment enhancement.