Physical binding of pyrene and phenanthrene to native and denatured DNA: Measurements by spectral and coupled-column liquid chromatography methods
✍ Scribed by Henry P. Nelson Jr.; Howard Devoe
- Book ID
- 102763652
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1984
- Tongue
- English
- Weight
- 790 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
The physical (noncovalent) binding of pyrene and phenanthrene to calf-thymus DNA in aqueous NaCl solutions was measured by a spectral method (analysis of absorption spectra by Henesi-Hildebrand plots) and a coupled-column liquid chromatography method (equilibration of DNA solutions with solid hydrocarbon in a generator column and analysis of dissolved hydrocarbon by liquid chromatography). The measurements yielded values of an affinity constant K' = n K , where n is the apparent number of binding sites per nucleotide and K is the apparent binding constant. The affinity of native DNA for pyrene decreases monotonically with increasing NaCl concentration, whereas the affinity of heat-denatured DNA exhibits a maximum at 0.10M NaCl. K' for the binding of phenanthrene to native DNA is an order of magnitude lower than K' for pyrene. The molar enthalpy for the binding of pyrene to native DNA in 10 mM NaCl is (-34.0 f 1 .0) kJ niol-'. The spectral method data indicate that 50 is an upper limit for the average number of base pairs between intercalation sites for pyrene along the DNA helix and that only a fraction of these sites are hound a t the highest binding ratios.