The fluorescence properties of a DNA probe

Abstract

Steady-state and dynamic fluorescence measurements have been performed on DAPI in solution and in complexes formed with a number of synthetic and natural polydeoxynucleotides. The decay of DAPI in buffer at pH 7 was decomposed using two exponentials having lifetime values of approximately 2.8 ns and 0.2 ns. The double exponential character of the decay was maintained over a large pH range from 3 to 9. At pH 1 the short component dominated, whereas at pH 12, only the long component was detectable. Two distinct spectra were associated with the two lifetime components; the short component was shifted to the red. The short lifetime component occurs in the presence of water. In water the excitation spectra depended on the emission wavelength and there was no viscosity dependence of the two forms. To explain these results we propose that there is a ground state conformer in which preferential solvation of the indole ring allows proton transfer in the excited state. DAPI complexed with polydeoxynucleotides retained most of the features of the decay of DAPI in solution. However, the complexes with fully AT-containing polymers stabilized the longer lifetime form of DAPI because the stronger binding enhanced solvent shielding. A gradual increase of the short lifetime component, which monitors dye solvent exposure, was obtained as the AT content was decreased. For polyd(GC) the decay was similar to that of free DAPI.

4-Hexylresorcinol inhibits transglutaminase-2 activity and has synergistic effects along with cisplatin in KB cells

“…the elongated average lifetime was attributed to the reduced contribution of the shorter lifetime component as well as the elongation and increased contribution of the longer lifetime component (Table I). According to previous studies, a short lifetime component (0.2 < τ < 0.6 ns) was assigned to a proton transfer in the excited state of the DAPI probe, while a long lifetime component (2.0 < τ < 4.0 ns) originated from a tightly bound DAPI-DnA complex (28,29). A relative contribution of a short lifetime component is, therefore, very useful to monitor solvent exposure of a DAPI-DnA complex.…”

Antiproliferative and Apoptotic Effects ofSesbania grandifloraLeaves in Human Cancer Cells

“…Overexpression of cyclin D1 has been reported in many cancers [19–21] and it was shown that the inhibition of cyclin D1 expression could help in the cancer treatments [22, 23]. In several studies, it was observed that the decrease in cyclin D1 levels is associated with apoptosis [24, 25]. In our present study, we observed a decrease in the expression levels of cyclin D1 which could have probably mediated the antiproliferative and apoptotic effects of the plant.…”

Fluorescence image cytometry of nuclear DNA content versus chromatin pattern: a comparative study of ten fluorochromes.

“…The two parameters describing the fluorescence pattem of the 2c hepatocytes, i.e., the intranuclear and internuclear SD of the fluorescence, proved to vary according to both the BP specificity and the binding mode of the fluorochromes. Although the specificity and the mode of binding of all these fluorochromes have been largely debated (Barcellona and Gratton, 1990;Darzynkiewicz, 1979;Crissman et al, 1978;Ardnt-Jovin and Jovin, 1977;Krishan, 1975;Muller and Gautier, 1975;Le Pecq and Paoletti, 1967;Ward et al, 1965) the fluorescence pattem has never been taken into account to ascertain the actual mode of binding to DNA in situ. In this respect, the results reported here provide new information.…”