SAXS-data-based structural modeling of DNA-gadolinium complexes fixed in particles of cholesteric liquid-crystalline dispersions

• Published in: European biophysics journal Vol. 39; no. 9; pp. 1313 - 1322
• Main Authors: Shtykova, E. V, Volkov, V. V, Salyanov, V. I, Yevdokimov, Yu. M
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01-08-2010; Springer-Verlag; Springer Nature B.V
• Subjects: Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biophysics; Cell Biology; Circular Dichroism; Deoxyribonucleic acid; DNA; DNA - chemistry; DNA - metabolism; DNA-based nanostructure; Dose-Response Relationship, Drug; Gadolinium; Gadolinium - chemistry; Gadolinium - metabolism; Gadolinium - pharmacology; Life Sciences; Ligands; Liquid Crystals - chemistry; Membrane Biology; Models, Molecular; Nanotechnology; Neurobiology; Nucleic Acid Conformation - drug effects; Original Paper; Salts - chemistry; Scattering, Small Angle; Small-angle X-ray scattering; Structural models; X-Ray Diffraction; DNA-based nanostructure; Modeling; Small-angle X-ray scattering; Circular dichroism
• ISSN: 0175-7571; 1432-1017
• DOI: 10.1007/s00249-010-0584-0

Structure of cholesteric liquid-crystalline dispersions (CLCDs) formed by double-stranded DNA molecules and treated with gadolinium salts was studied by small-angle X-ray scattering (SAXS). The obtained SAXS data open the way for structural modeling of these complexes to obtain a reasonable explanation for the correlated decrease in amplitude of an abnormal negative band in the circular dichroism (CD) spectra and the characteristic Bragg peak in the experimental small-angle X-ray scattering curves observed on treatment of CLCD by gadolinium salts. Model simulations of different kinds of structural organizations of the DNA-gadolinium complex were performed using novel SAXS data analysis methods in combination with several new, complementary modeling techniques, enabling us to build low-resolution three-dimensional structural models of DNA-gadolinium complexes fixed in CLCD particles. The obtained models allow us to suggest that a change takes place in the helical twist of quasinematic layers formed by these molecules at high concentrations of gadolinium salt. This change in the twist can be used to explain the experimentally observed increase in amplitude of an abnormal band in the CD spectra of DNA CLCD.