Structural determination, thymus

Small-angle X-ray scattering (SAXS), circular dichroism (CD), and UV spectroscopy at different temperatures were used to investigate the nature of calf-thymus DNA in aqueous solution, in the presence of [Me Sn] " (n = 1-3) species. The results demonstrate that the [MeSn(IV)] moiety does not influence the structure and conformation of the DNA double helix, and does not degrade DNA, as indicated by agarose gel electrophoresis. Inter alia, the radii of gyration, Rg, of the cross section of native calf-thymus DNA, determined by SAXS in aqueous solution in the presence of [Me Sn] " (n = 1-3) species are constant and independent of the nature and concentration of the [Me Sn] species. 

The local structure of these complexes and adducts of calf-thymus DNA with different organotin(IV) moieties were determined by means of EXAFS. The... 

Thermal denaturation of calf-thymus DNA has also been studied by SERS-spectro-scopy The examinations of the SER scattering of thermally denatured DNA indicates that the nucleic bases bands are sensitive to the termal transition from the helical double stranded structure to the disordered single stranded structure. In this thermally destabilized DNA the strands are open and the corresponding bases can easily re-orientate therfore becoming available for direct interaction with the surface. Generally at every adsorption potential there is a sensitive increase of the intensity of the Raman bands of the nucleic bases in the SERS spectra. In summary, one may say that SERS is useful to determine the structural changes of DNA under the action of physical or chemical disturbances. 

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