Influence of alkali cation nature on structural transitions and reactions of biopolyelectrolytes.
A general thermodynamic analysis is presented, describing how counterion species of different nature, but the same valency, influence polyelectrolyte transformations and reactions of the general form: PA1.B1-M(+)-->PA2.B2M+ + (B1 - B2)M+. Here PA1 and PA2 are two different states or structural forms of a polyanion, B1 and B2 are the number of M+ ions thermodynamically bound to the polyanions PA1 and PA2, respectively. The specific effects of the two counterions, M1+ and M2+, on this equilibrium can be simply related to the quotient of their selectivity constants, D2M2M1/D1M2M1, for the polyion states 1 and 2. We analyze how different monovalent counterions (particularly, sodium and potassium) affect polyelectrolyte reactions and transformations such as, e.g., the DNA helix-coil transition. Previous experimental results on the competition between DNA and the synthetic polyanion, poly(methacrylic acid), for binding to the synthetic polycation, poly(N-ethylvinylpyridinium), has been investigated with respect to sodium and potassium ion specificity, using our model. We also discuss the DNA-histone disassembly/assembly reaction modeled as a competition of two polyanions for binding to a polycation.
Korolev
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Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91, Stockholm, Sweden. korolev@physc.su.se
Nordenskiöld
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D000179:Acrylates / Q000737:chemistry; D000465:Algorithms; D004247:DNA / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D006657:Histones / Q000737:chemistry; D008024:Ligands; D009690:Nucleic Acid Conformation; D011099:Polyglutamic Acid / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D013816:Thermodynamics
D000179:Acrylates; D004573:Electrolytes; D006657:Histones; D008024:Ligands; D011108:Polymers; D011099:Polyglutamic Acid; D004247:DNA; D012964:Sodium; D011188:Potassium