A Transition in DNA Molecule’s Spatial Ordering Due to Nano-Scale Structural Changes
نویسندگان
چکیده
The optical, X-rayand AFM-properties of the particles of cholesteric liquid-crystalline dispersion (CLCD) formed by double-stranded DNA molecules and treated with gadolinium salts are studied. It is shown that under certain conditions this treatment results in two effects: i)amplification of the abnormal negative band in the CD spectra specific to the initial CLCD, and ii) disappearance of small-angle X-ray scattering specific of ordered DNA molecules. The explanation of these effects is based on a suggestion that gadolinium ions when present at high concentrations not only induce nano-scale changes in the DNA secondary structure, but also overcompensate the DNA negative charges, influencing the efficiency of DNA-DNA interactions in the content of the particles of CLCD. These processes lead to transformation of the spatial structure in particles of CLCD. The resulting structure of particles of DNA CLCD highly enriched in gadolinium is not “liquid-crystalline”; rather it is a rigid construction of practical importance.
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