Untitled

Liquid-Crystalline Dispersions of Double-Stranded DNA

“…The analysis of more than 10 DAU analogues, which differ by the presence and the position of substituents at the aglycon, has shown that the presence of reactive oxygen atoms in the 5, 6 and 11, 12 positions of anthracyclines is one of the essential conditions for the amplification of abnormal optical activity upon building of cross-links (chelate bridges). Consequently, each copper atom in the bridge forms 4 bonds with coplanar oxygen atoms [87]. This reflects the well-known stereochemical and electronic properties of chelate complexes in which Cu 2+ ions interact with 4 oxygen atoms of anthracyclines [81,[88][89][90].…”

“…Taking into account the distance between ds DNA molecules in dispersion particles formed at C PEG = 170 mg•mL −1 , the results obtained by low-temperature magnetometry and supported by the theoretical calculations [87,[92][93][94] allow one to accept that the nanobridge between adjacent ds DNA molecules contains six Cu 2+ ions. Besides, the theoretical evaluations, based on the analysis of the dependences of the amplitude of the band at λ~510 nm on the number of DAU molecules (an isotropically oriented near ds DNA surface) and on the number of copper atoms [92,93] has shown that one nanobridge in dispersion particles (at C PEG = 170 mg•mL −1 ) can include from four to six DAU molecules and its final structure is shown in Figure 15c.…”

DNA Liquid-Crystalline Dispersion Particles as a Platform for Creation of “RIGID” Spatial Structures

“…These groups maybe formed by metal ions specifically fixed in a groove (grooves) on the DNA surface or by chemical groups in the content of planar compounds, which form the complexes with ds DNA molecules. Taking into account the steric location of the DNA reactive groups (in particular, the N-7 atoms of purines) in the grooves on the surface of the ds DNA molecules, it is evident that two neighboring ds DNA molecules must be sterically "phased" to realize the cross-linking of the same reactive groups) [39]. ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡ Taking into account that the distance between ds DNA molecules in the CLCD particles (2.5-5.0 nm), depending on osmotic pressure of a solution) the chemical cross-links have been named as "nanobridges" [40].…”

“…The chelation process may result in formation of flat polymeric bridge involving a few anthracycline molecules (Fig. 10, IV) linked by bivalent metal ions [39]. Analysis of the various anthracyclines that differ by the presence and the location of aglycone substituents has shown that one of the basic prerequisite for the formation of extended flat complexes is the presence of reactive oxygen atoms at the positions 5, 6 and 11, 12 (or 1,2) of anthracycline aglycone (Fig.…”

“…The theoretical evaluations [39,51,[56][57][58][59] showed that one nanobridge can include from four to six ions. The direct magnetometric estimation of Cu 2+ cations [60] in the content of ds DNA CLCD particles demonstrated that one nanobridge between ds DNA molecules fixed in the content of CLCD particles formed at C PEG = 170 mg/ml can contain from four to six copper ions.…”