The structural diversity of DNA–neutral phospholipids–divalent metal cations aggregates: a small-angle synchrotron X-ray diffraction study

Abstract

SummaryWe investigate the structure of aggregates formed due to DNA interaction with saturated neutral phosphatidylcholines (DPPC and DMPC) in presence of Ca 2+ and Mg 2+ cations using simultaneous synchrotron small-and wide-angle X-ray diffraction. For

The structural variety of DNA-DPPC-divalent metal cation aggregates: SAXD and SANS study

“…1. When heating the aggregates to higher temperatures, we have observed an increase in the DNA peak width and a decrease of its intensity, which gradually disappears in the background (see also [13]). The typical diffractogram DNA+DPPC+ion 2+ aggregates prepared with highly polymerized calf thymus DNA at temperatures t≥50 o C is shown in Fig.…”

“…Either redistilled water or D 2 O (99.9 %, Merck, Germany) were used for the preparation of solutions. Samples were prepared by hydration of a thin lipid film (~5-10 mg of lipid per sample) with a solution of DNA and cations to obtain the required molar ratio lipid : DNA base and concentration of ions (more details in [13]). Multilamellar vesicles prepared from fully hydrated pure DPPC were used as reference sample.…”

“…Structural polymorphism of DNA+PC+cation (Ca 2+ , Mg 2+ ) as a function of cation concentration and temperature were examined in our previous works [12,13]. The binding site for cations is near the negative phosphate group of the P --N + dipole of phospholipid headgroup [14,15].…”

Study of electrostatic energy contribution on monolayer domains size

“…In this study we demonstrate on phospholipid monolayer the effect of magnesium ions (Mg 2+ ), which are important for biophysical applications [10,11]. Various experiments were already done in this field; however, without any detail physical analysis.…”

Electrolyte Solution at Zwitterionic Lipid Layer

“…5 On the contrary, naturally occurring zwitterionic lipids are biodegradable and nontoxic, but the attractive interaction between zwitterionic lipid layers and DNA can be induced by multivalent ions. [6][7][8][9] The classical mean field approach to describe electrostatic interactions between charged systems in electrolyte solutions is the Poisson-Boltzmann (PB) method. Within the PB theory ions are modelled as point charges, while the solvent (water) is accounted for by a uniform dielectric constant.…”