In this paper, written upon editor’s invitation in a journal with high impact factor (8.651), association and formation of ordered structures in mixtures of vinyl polyelectrolytes and cationic surfactants is treated. It is demonstrated that polyion charge density, rigidity, its stereoregular structure (tacticity), and eventual presence of hydrophobic groups play a decisive role in interactions and formation of liquid crystalline structures. Various thermodynamic and transport properties of polyionsurfactant ion complexes are presented.
COBISS.SI-ID: 34100741
Progress in understanding the molecular basis of some important cellular processes is rather slow due to the lack of knowledge of forces that drive folding of G-quadruplex structures in guaninerich DNA sequences. In the current work, we performed a comprehensive global thermodynamic analysis of calorimetric and spectroscopic data obtained on monitoring the folding/unfolding of human telomeric DNA induced by changes of temperature and/or salt concentration. We show that unfolding of human telomeric DNA may be described as a monomolecular equilibrium process that involves thermodynamically distinguishable folded, intermediate, and unfolded state. Our results represent the first experimental support of the theoretically predicted sequential unfolding/folding mechanism of human telomeric DNA.
COBISS.SI-ID: 36015365
Using molecular dynamics simulations, we study ion−ion correlations in water. We study the potentials of mean force for the full set of alkali halide ion pairs, and we test different parameter sets for modeling the water and the ions. We also calculate association equilibrium constants and compare them to experiments. From observations on the relative depths of the free energies of the contact and the solventshared ion pair, we find a good correlation with Collins proposition: two small and two large ions should associate in water, and small−large combination of ions should be more dissociated.
COBISS.SI-ID: 30430213
A new folding intermediate (i-Oxy-1.5) of Oxytricha nova telomeric Oxy-1.5 G-quadruplex was characterized in aqueous solution using NMR spectroscopy, native gel electrophoresis, thermal differential spectra (TDS), CD spectroscopy, and differential scanning calorimetry (DSC). Kinetic analysis of potassium ioninduced structural transitions shows that folding of Oxy-1.5 G-quadruplex from i-Oxy-1.5 is much faster and proceeds through less intermediates than folding from single strands. Therefore, a new folding pathway of Oxy-1.5 G-quadruplex is proposed. This study provides evidence that guaninerich DNA sequences can selfassemble into specific preorganized DNA structures that are predisposed to fold into G-quadruplex when interacting with cations such as potassium ions.
COBISS.SI-ID: 1701423
The effect of different cations and anions on the micellization of a biocompatible zwitterionic surfactant CHAPS has been examined in water, LiCl, CsCl, NaBr, and NaI aqueous and buffer solutions. It turned out that CHAPS behaves as a weakly charged cationic surfactant in salt solutions and as a nonionic surfactant in water and buffer medium. All thermodynamic parameters of micellization were estimated by fitting the model equation based on the mass action model to the experimental data. The aggregation numbers of CHAPS surfactant around critical micelle concentration, obtained by the fitting procedure, are considerably low (~ 5). Furthermore, some predictions about the hydration of the micelle interior based on the correlation between heat capacity change and changes in solventaccessible surface upon micellization were made. CHAPS molecules are believed to stay in contact with water upon aggregation, which is somehow similar to the micellization of short alkyl chain cationic surfactants.
COBISS.SI-ID: 36016389