Salt-induced conformational changes

Hirata, F. Levy, R. M. Salt-induced conformational changes in DNA analysis using the RISM theory. J. Phys. Chem. 1989 93 479-484. 

F. Hirata and R. M. Levy, /. Phys. Chem., 93, 479 (1989). Salt-Induced Conformational Changes in DNA Analysis Using the Polymer RiSM Theory. 

Within the PB cell model, the counterion concentration at the outer boundary gives the osmotic pressure, which is a measure of the electrostatic repulsion between neighboring biomolecules. This pressure can also be experimentally determined. " " The Donnan coefficient, on the other hand, is strongly influenced by conditions at the macromolecular surface and can be used to provide key insight into the nature of polyelectrolyte-counterion interaction. " This interaction is important because of the salt-induced conformational changes DNA undergoes. The nature of this behavior is believed to arise from the partial collapse, or condensation. 

Mahy NL, Perry PE, Gilchrist S, Baldock RA, Bickmore WA (2002) Spatial organization of active and inactive genes and noncoding DNA within chromosome territories. J Cell Biol 157 579-589 Mangenot S, Leforestier A, Vachette P, Durand D, Livolant F (2002) Salt-induced conformation and interaction changes of nucleosome core particles. Biophys J 82 345-356 Marsden MP, Laeimnh UK (1979) Metaphase chromosome structure evidence for a radial loop model. Cell 17 849-858... 

Mangenot, S., Leforestier, A., Vachette, P., Durand, D., and Livolant, F. (2002) Salt-induced conformation and interaction changes of nucleosome core particles. Biophys. J. 82, 345-356. 

The methyl group is the smallest polyhedral substituent which can interact with its neighbors. Its intimate behavior is of primary importance for the quantitative treatment of steric effects, since it is often taken (as a combined atom) as a reference for the size of alkyl groups (Section II). The conformational aspect of the steric size of a methyl and its ability to induce conformational changes was clearly evident in the study of various poly-methylisopropylpyridines or -pyridinium salts 81a-e (83T4209) (Scheme 63). 

Attempts to induce conformational changes showed that a second fourfold helix, having a slightly larger repeat (3.72 nm) can be obtained by addition of chondroitin 6-sulfate to the hyaluronate solution. It is not possible to induce a change from the threefold to the fourfold helical form in the condensed state, but the reverse can be achieved, although only by the addition of a calcium salt. A review of the hyaluronic acid conformations was given. 

The molecule with the charge distribution (73) can be considered as a model for a B-DNA hehx charges on the strands represent the phosphates and the cylinder charge corresponds to adsorbed cations, smeared on the DNA surface (for B-DNA, a 10 A, B 0.4 H [182]). Note that (74) could also be used for the description of electrostatically induced conformational changes of DNA, e.g., for the B- to Z-DNA transition at high salt concentrations [183]. Moreover, the exact theory of electrostatic interaction between two DNA duplexes predicts an attraction between them due to a correlated structure-driven zipper-like charge separation along the molecules [184]. 

Salt Concentration and Type-induced Conformational Change of Grafted Polyelectrolytes... 

Mitsui et al. (1970) reported an unusual X-ray diffraction pattern of ethanol-precipitated fiber of poly(dIdC) poly(dIdC) and proposed a left-handed helical structure for this copolymer. Pohl and Jovin (1972) found that poly(dGdC)-poly(dGdC) underwent a salt-induced conformational transition in solution to a new form with an inverted CD spectrum and suggested that a left-handed helix could be a possible explanation. Subsequently, Pohl (1976) also observed the same CD spectral change for... 

All this leads to the question of how DNA affects nucleosomal stability at the molecular level. DNA bendability has been repeatedly put forward as a candidate to play an important role [280-282]. This property is related to the persistence length of DNA [283]. A study on the characterization of nucleosomes reconstituted onto methylated DNA [poly(dG-m dC) poly (dG-m dC)] [284] provides support to this hypothesis. Poly(dG-m dC) poly (dG-m dQ DNA can be induced to change from its B to its Z conformation in the presence of millimolar amounts of divalent ions [285] such as MgCl2. The persistence length of poly(dG-m dC) poly (dG-m dC) in the Z form in high salt was found to be 208 nm (ca. 612 bp) [286], a value much lower than that of the same polymer in the B form (93.8 nm, 276 bp) at... 

Sucrose octasulfate (23, Structures 6) bound to FGF and was able to induce, like heparin, a conformational change in the peptide, but showed very low mitogenic activity for an F32 cell line. The basic aluminium salt of sucrose octasulfate, which is used as a drug (Sucralfate, Carafate) for the treatment of duodenal ulcers was claimed to exert part of its activity through the stabilization of FGF... 

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