Solvent Effects on the Kinetics of the Interaction of 1-Pyrenecarboxaldehyde with Calf Thymus DNA

Abstract

The kinetics of the interaction of a fluorescent probe, 1-pyrenecarboxaldehyde, with calf thymus DNA has been studied in different water/alcohol mixtures (ethanol, 2-propanol, and ter-butanol) at 25 degrees C, by using the stopped flow technique. The kinetic curves are biexponential and reveal the presence of two processes whose rates differ by about 1 order of magnitude on the time scale. The dependence of the reciprocal fast relaxation time on the DNA concentration is linear, whereas the concentration dependence of the reciprocal slow relaxation time tends to a plateau at high DNA concentrations. The simplest mechanism consistent with the kinetic results involves a simple two-step series mechanism reaction scheme. The first step corresponds to the formation of a precursor complex, (DNA/Py)(I), while the second one corresponds to full intercalation of the pyrene dye between the DNA base pairs. The values of the rate constants of both steps decrease as water activity decreases. The results have been discussed in terms of solvation of the species and changes in the viscosity of the solution.

YM155 inhibits topoisomerase function

“…Each addition was followed by an equilibration time of 20 min before the flow times were measured. The intrinsic viscosities were proportional to the flow times of the solutions and calculated as given in literature [40]. …”

Experimental and computational thermodynamics of pyrene and 1-pyrenecarboxaldehyde and their photophysical properties

“…The conformational changes induced upon the binding of the target analyte to the pyrene-appended complexes are monitored using the pyrene luminescence emission, due to the fluorescent properties changes between the complexes and the isolated pyrene units. Pyrene and 1-pyrenecarboxaldehyde find application as fluorescence probes [21,22], useful in biophysical studies of multimolecular aggregates. Moreover, 1-pyrenecarboxaldehyde has been incorporated in Langmuir-Blodgett films, with potential application in sensors and optoelectronic devices [23].…”

Binding of DNA by a dinitro-diester calix[4]arene: Denaturation and condensation of DNA

“…Polynucleotide concentration, given by phosphate groups, was determined spectrophotometrically from molar absorptivity (6600 mol −1 dm 3 cm −1 at 258 nm) [33]. An agarose gel electrophoresis test using ethidium bromide indicated that the average number of base pairs per DNA molecule is above 10,000 bp [34]. The ratios in absorbance at 260 and 280 nm of the solutions were found to be between 1.8 and 1.9, which suggested the absence of proteins [35].…”